Details on Princess Diana and her stepmother, Raine Spencer, unearthed in new documentary (Exclusive)

A revealing new documentary is shedding light on Princess Diana's contentious stepmother, Raine Spencer.

"Princess Diana's 'Wicked' Stepmother," which premieres on the Smithsonian Channel on Monday, October 28, at 8 p.m. EST, spotlights Diana and Raine's bitter rivalry that comes to take a surprising turn later in their lives.

In a clip from the documentary available exclusively on AOL, which you can watch at the top of the page, royal experts and other insiders give insights into the mysterious People's Princes and her complicated relationship with Raine.

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Raine Spencer, stepmother of Princess Diana, through the years
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Raine Spencer, stepmother of Princess Diana, through the years
LONDON, UNITED KINGDOM - JUNE 02: Princess Diana Talking With Raine, Comtesse De Chambrun (previously Her Stepmother, Countess Raine Spencer) At A Private Viewing And Reception At Christies Of Dresses Worn By The Princess That Are For Auction To Raise Money For The Aids Crisis Trust And The Royal Marsden Hospital Cancer Fund. (Photo by Tim Graham/Getty Images)
Earl Spencer and Wife Raine (Photo by �� Quadrillion/CORBIS/Corbis via Getty Images)
The wedding of Raine Spencer and Gerald Legge, Earl of Dartmouth, St Margaret's Church, Westminster, London, July 21st 1948. (Photo by Keystone/Hulton Archive/Getty Images)
7th December 1971: From left to right, Dr Roy Strong, director of the National Portrait Gallery, Countess Dartmouth, later Raine Spencer, and cartoonist Osbert Lancaster at a party celebrating freedom for part of Somerset House in London. (Photo by John Minihan/Evening Standard/Getty Images)
Diana, The Princess Of Wales Has Lunch With Her Stepmother Raine Spencer At The Connaught Hotel In Mayfair. (Photo by Antony Jones/UK Press via Getty Images)
Lady Diana's father Edward Spencer and his wife Raine McCorquodale in Paris in 1980. (Photo by Bertrand Rindoff Petroff/Getty Images)
UNITED KINGDOM - JANUARY 01: Earl Spencer and his wife Raine in front of their home at Althorpe House (Photo by Tim Graham/Getty Images)
LONDON - FEBRUARY 24 Earl Spencer and his wife Raine Spencer meet the public outside Buckingham Palace after the announcement that Diana Spencer is to marry Prince Charles February 24, 1981 in London, England. (Photo by Anwar Hussein/Getty Images)
1984: Raine, Countess Spencer with a bouffant hair do. She is the step-mother of Diana, Princess of Wales and daughter of novelist Barbara Cartland. (Photo by Hulton Archive/Getty Images)
20th May 1985: The Earl (1924 - 1992) and Countess Spencer arriving at Spencer House for the 21st birthday of the Earl's son, Viscount Charles Althorp. The Earl is the father of Princess Diana and Prince Charles' father-in-law. (Photo by Hulton Archive/Getty Images)
ALTHORP, UNITED KINGDOM - SEPTEMBER 16: Earl Spencer And His Wife Raine At The Wedding Of His Son Charles, Viscount Althorp In Northamptonshire. (raine Mccorquodale, Countess Raine De Chambrun). (Photo by Tim Graham/Getty Images)
LONDON, UNITED KINGDOM - JANUARY 01: Earl Spencer And His Wife Raine Spencer Visiting Princess Diana In Kensington Palace. (raine Mccorquodale, Countess Raine De Chambrun Circa 1990s (Photo by Tim Graham/Getty Images)
UNITED KINGDOM - MAY 19: Countess Raine Spencer, stepmother of the Princess of Wales (Photo by Tim Graham/Getty Images)
LONDON, UNITED KINGDOM - DECEMBER 14: Raine, Comtesse De Chambrun (countess Raine Spencer) At A Gala Performance By The English National Ballet At The Banqueting House, Whitehall. (Photo by Tim Graham/Getty Images)
Raine Spencer Attends A Gala Reception & Preview Of Her 'Dresses Auction' At Christies In London. (Photo by Antony Jones/UK Press via Getty Images)
LONDON, ENGLAND - SEPTEMBER 6: Raine, Countess Spencer arrives at The Funeral of Diana Princess of Wales at Westminster Abbey, London, on September 6, 1997, in London, England. (Photo by Julian Parker/UK Press via Getty Images)
LONDON, UNITED KINGDOM - MAY 12; Raine, Countess Spencer attends her 70th Birthday party at the Ritz Hotel, on May 12, 1999 in, London, United Kingdom..( Photo by UK Press via Getty Images )
UNITED KINGDOM - JUNE 26: Raine Spencer, Hardy Amies Royal Academy Fashion Show Gala Evening, To Raise Money For The Academy, London (Photo by Dave Benett/Getty Images)
LONDON, UNITED KINGDOM - FEBRUARY 17: Raine, Countess Spencer At The Banquet Hosted By The Queen Of Denmark At The Natural History Museum In London. (Photo by Tim Graham/Getty Images)
LONDON - JUNE 6: (EMBARGOED FOR PUBLICATION IN UK TABLOID NEWSPAPERS UNTIL 48 HOURS AFTER CREATE DATE AND TIME) Raine Countess Spencer attends the annual summer party at Sotheby's, New Bond Street on June 6, 2005 in London, England. (Photo by Dave Benett/Getty Images)
LONDON - SEPTEMBER 9: Raine Spencer attends the 'Made In Italy' party at Harrods to launch their new Italian ranges on September 9, 2004 in Knightsbridge, London. (Photo by David Westing/Getty Images)
Raine, Countess Spencer attends Christmas party in honour of Dame Shirley Bassey to celebrate her 70th Birthday, kindly hosted by Von Essem Chairman, Mr Andrew Davis at Cliveden House on December 16, 2007 in Berkshire, England. (Photo by Jon Furniss/WireImage)
Lady Raine Spencer attend the launch ceremony for an in-store promotion of Malaysian craft at Harrods on February 26, 2009 in London, England. (Photo by Fred Duval/FilmMagic)
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"She was bitterly unhappy. She was disappointed in her marriage, as was Charles. It was a car crash from the very beginning and Diana used to take herself back home to Althorp and hide herself away in her room but not see anybody," royals biographer Penny Junor says in the film. "She was just really miserable. Poor Diana, she didn't have a solid family. She didn't have a mother, Althorp clearly was home."

While her mother moved back to Scotland and remarried, her father married Raine Legge in 1976. Soon thereafter, the woman deemed "Acid Raine" by Diana began to sell off the "treasure trove" of artworks and fineries at the Spencer estate "in a secretive manner," as "Raine & Johnnie" author Angela Levin explains in the AOL exclusive clip.

"Princess Diana's 'Wicked' Stepmother" premieres on the Smithsonian Channel on Monday, October 28, at 8 p.m. EST

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9 secrets about Princess Diana no one knew about until after her death
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9 secrets about Princess Diana no one knew about until after her death

She recorded her thoughts on tape

Much of what we know about Princess Diana’s personal life is thanks to audiotapes she recorded herself. Once she recognized her marriage to Prince Charles was falling apart, she documented her side of the story on a tape recorder and gave the tapes to her close friend, Dr. James Colthurst. He, in turn, gave them to journalist Andrew Morton so her words could get out to the public. From those tapes, Morton published the biography DIANA: Her True Story—In Her Own Words in 1992. No one knew Diana had a hand in the book’s production until after her death. Here are some more surprising facts you probably didn't know about Princess Diana.

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Her sister dated Prince Charles

There are definitely ways to improve your relationship with your sibling, but we’re not sure if sharing a boyfriend is one of them. Before Diana and Charles started going steady, he dated her sister, Sarah. She introduced the two when Diana was just 16 and takes credit for their falling in love, calling herself Cupid.

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Her grandmother worked for the queen

As prominent a public figure as Queen Elizabeth is, there’s still a lot that the public doesn’t know about her. One of those more intriguing bits of trivia is that the Queen Mother was close friends with Princess Diana’s grandmother, Ruth Fermoy. She was one of Her Majesty’s ladies-in-waiting and later held the title Woman of the Bedchamber, which meant that she was the Queen’s right-hand woman and assisted with important social engagements. Here are some more facts (and scandals!) you never knew about Queen Elizabeth II.

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She and her husband were related

The royal family tree can get pretty complicated, but don’t worry, there’s nothing incestuous about this marriage. Princess Di and Prince Charles were distantly related. Specifically, they were 16th cousins once removed, through King Henry VII.

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She had a poor sex life

In her tape recordings, Princess Diana discussed her married life in great detail, even calling her wedding day “the worst day of her life.” Specifically, she talked at length about her lack of a sex life, saying that she and her husband had sex but it was “very odd.” By the time she made the recordings, their sex life had been going downhill for seven years. She went on to say, “There was no requirement for (sex) from his case. Sort of once every three weeks… and I kept thinking it followed a pattern. He used to see his lady (Camilla) once every three weeks before we got married.” Learn more about the real story of what happened between Charles and Diana.

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She messed up her wedding vows

In hindsight, Princess Diana messing up her wedding vows may seem like a sign her marriage was bound to fail, but in reality, she just caught a case of wedding day jitters. During the vows, she called her husband “Philip Charles” instead of “Charles Philip,” mixing up his first and middle names. Here are some more little mistakes that happened on royal wedding days.

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She ate in the kitchen

It was against royal family etiquette to eat in the kitchen with staffers and not in a dining room, but Princess Diana was no stranger to breaking protocol. Her personal chef, Darren McGrady, said she would just walk into the kitchen and eat at a countertop while he tidied up, which was unheard of coming from any royal. She would even make coffee for the two of them. Check out these stunning, rarely seen photos of the People's Princess.

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She attempted suicide

One of the most troubling revelations from Princess Diana’s audiotapes was that she struggled with depression and even attempted to take her own life. She said in her recordings, “I was so depressed, and I was trying to cut my wrists with razor blades.” She also talked about having bulimia and that the eating disorder started after Prince Charles put his hand on her waist and said, “A bit chubby here, aren’t we?”

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She was harassed by the paparazzi

With three new documentaries about Princess Diana set to premiere, Prince William and Prince Harry are opening up about their memories of their mother. Some are uplifting, like how she involved them in her charitable work. But their recollections of Diana dealing with the paparazzi are disturbing. As Prince William says in the ITV and HBO documentary, Diana, Our Mother: Her Life and Legacy: “If you are the Princess of Wales and you’re a mother, I don’t believe being chased by 30 guys on motorbikes who block your path, who spit at you to get a reaction from you and make a woman cry in public to get a photograph, is appropriate. Harry and I, we had to live through that.” Here's how Prince Harry and Prince William are keeping their mother's memory alive twenty years after her death.

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