Katie Cassidy on father David Cassidy: What the world 'doesn't know'

Katie Cassidy is ready to speak more openly about her father, the late David Cassidy.

It's long been known that the "Arrow" star had a complicated relationship with David, although few details were known about just how messy it was.

"I didn't meet my father until I was in the fourth grade," Katie told Us Weekly. "The world doesn’t know that. Not because I’m hiding it, it just hasn’t been discussed."

Now 31 years old, Katie said that at a time, she and David had a great relationship, but that may not have been the case in recent years.

“My biological father and I had a really good relationship at one point," she said. "He was one of my close friends and gave me wonderful advice."

But although David was a "wonderful, wonderful person," Katie said, "sadly, he had some demons. There is a silver lining in all of that. You live and learn and it has brought my family closer together so I’m grateful for that."

David Cassidy died at 67, not long after publicly sharing his dementia diagnosis. He had a long history of substance abuse dating nearly as far back as his "Partridge Family" days.

After his death, headlines swirled that the actor/singer had left Katie out of his will.

Katie, for her part, is moving forward with positive updates in her life: She's engaged to marry later this year.