Barbara Walters Gets Inside Heche's Head

September 4 -- (ABCNEWS.com) — Anne Heche says the sexual molestation she suffered at the hands of her father caused her to escape into a "fourth dimension" fantasy world in which she believed she was from another planet.

"I'm not crazy," Heche tells 20/20 on Wednesday in an exclusive interview with Barbara Walters. "But it's a crazy life. I was raised in a crazy family and it took 31 years to get the crazy out of me."

In the wide-ranging interview, Heche, 32, talks about her childhood, her career, her relationship with Ellen DeGeneres — she says her first night with the comedian was "the best sex I'd ever had" — and new love Coleman "Coley" Laffoon, a 27-year-old cameraman whom she married on Saturday.

Heche, promoting her new book, Call Me Crazy, says she's had a lifelong battle with mental illness. "I had a fantasy world that I escaped to. I called my other personality Celestia," she explains. "I believed I was from that world. I believed I was from another planet. I think I was insane."

Heche traces much of her psychological trauma to sexual abuse she says she suffered at the hands of her father, Donald, a choir director in a Baptist church. She reveals that upon learning of her father's history of homosexual encounters, shortly prior to his AIDS-related death in 1983, she feared for her life.

Her traumatic childhood was a factor in her decision to date comedian Steve Martin, 24 years her senior. "I wanted the love of an older man. I wanted comfort. I wanted humor. I wanted all of the things that he offered," she says. "Why did we break up? There's wasn't anything wrong with Steve. It was just that it was not what I wanted to commit my life to."

Neither, it turns out, was her relationship with DeGeneres, though she vividly recalls their initial encounter, on Oscar night in 1997: "I saw the most ravishing woman I had ever seen in my life standing across the room. Her name was Ellen DeGeneres. She was radiating. I think at certain times in people's lives you just radiate an energy and a glow of fabulousness. And that was her. I had never seen anybody so lit up."