Former child-star Mackenzie Phillips, whose life has been marred by drug abuse and arrests, confessed today that she engaged in a 10-year consensual sexual relationship with her father, rock star John Phillips.

The actress claims she was raped by her father when she was 19. Phillips, 49, the former star of '70s-'80s sitcom "One Day at a Time," told Oprah Winfrey that she was first raped by her father in a hotel room when she was 18 while passed out after a drug binge but continued to use drugs and have consensual sex with him for years.

The relationship continued long after she married Jeff Sessler when she was 19, and ended only when she became pregnant and feared her father was the baby's father, Phillips said. John Phillips, she said, paid for an abortion.

Reading an excerpt from her new book, "High on Arrival," on Winfrey's show today, Phillips said of her first sexual experience with her father: "I woke up that night from a blackout to find myself having sex with my father. I don't know how it started." She was raped by her father, lead singer of the Mamas and the Papas, in the hotel room in the late 1970s, Phillips said.

Mackenzie Phillips told Winfrey she confronted her father about the rape, but he characterized their relationship as romantic, Mackenzie said. "After the first experience, I went to my father and said we need to talk about how you raped me. My dad said: 'Raped you? Don't you mean made love?' In that moment, I thought I'm really on my own here."

In 1980, soon after she'd been fired from "One Day at a Time" because of her out-of-control drug use, Phillips began to travel with her father's new band, the New Mamas and the Papas. It was during that time, she said, that she began regularly doing drugs and having sex with her father. "It didn't happen every day, it didn't happen every week, but it certainly happened and happened many times," she said.

Phillips thought she was "going to hell" for repeatedly having sex with her own dad during a relationship that became so twisted that he even suggested they get married, she claims. She said the years of sex with her hippie-dippie dad -- who, like her, was a heavy drug user -- came to an end only when she became pregnant and had an abortion, fearing the child was his.