Kennedy patriarch's mistress tells all, says his wife approved of their affair

While the Kennedy family has long kept many stories behind closed doors, the longtime mistress of Kennedy patriarch Joseph P. Kennedy is spilling a ton in her new self-published memoir.

Janet Fontaine, now 91, published A Good Life, a book about her dalliances with Kennedy while she lived with the family in their Hyannis Port mansion and how her nine-year affair was carried out right under his wife, Rose's nose.

Fontaine revealed to People that her affair with Joe began soon after he hired her as his personal assistant in 1948. At the time, she was 24 and he was 60. ​Joe had already been married to his wife, Rose, for 34 years but according to Fontaine, she hardly paid any mind to Joe's infidelity.

Rose accepted me with open arms, was very fond of me and treated me beautifully. I have no hard feelings toward her," Fontaine told People. "Joe and Rose were not close but they respected one another. There was a loneliness in his life. Joe had just lost his son, Joe Jr., in the war and then four months after I went to work for him, he lost Kathleen, his favorite daughter [in a plane crash]. He used to cry and say 'I can't talk about them.' I think he needed someone to cling to and bring little segment of happiness to his life."

Throughout the time she spent with the family, Fontaine says got close to them and Joe was extremely charismatic.

"I spent a great deal of time at their homes in Hyannis Port [Massachusetts] and Palm Beach," Fontaine explained.

In fact, it was at the Palm Beach home that Joe first seduced Fontaine, who was a virgin at the time.

"Joe was not surprised that I had not had sex," she said in an interview with Ronald Kessler. "He taught me everything."

Adding that he wasn't particularly difficult to fall for. "He was fun, he was warm, he was thoughtful, never demanding, very considerate, and very gentle," she said. "It wasn't very difficult to fall in love with him. He was very charming. He overwhelmed me."

The new book certainly adds another level of public intrigue to the often elusive family. Fontaine's book is available at Amazon.