I am stunned and disturbed by the allegations made by Mackenzie Phillips in her memoir about the sexual relationship she had with her father. Then to find out it was actually him who got her hooked on heroin and introduced her to the drugs that eventually destroyed her life, it’s no wonder she has battled demons her entire life.

Mackenzie Phillips, the daughter of The Mamas And The Papas star John Phillips, has revealed she had a long-term sexual relationship with the musician.

In an explosive tell-all memoir, “High on Arrival,” Mackenzie Phillips says she was drugged and raped by her famous father when she was 19-years-old and went on to engage in a consensual incestuous affair with the singer.

Phillips, now 49, reveals their first sexual encounter happened the night before she married Jeff Sessler, a member of the Rolling Stones entourage. ‘On the eve of my wedding, my father showed up, determined to stop it,’ writes Phillips in her new memoir “High on Arrival.” ‘I had tons of pills, and Dad had tons of everything too. Eventually I passed out on Dad’s bed. My father was not a man with boundaries. He was full of love, and he was sick with drugs. I woke up that night from a blackout to find myself having sex with my own father. Had this happened before? I didn’t know. All I can say is it was the first time I was aware of it. For a moment I was in my body, in that horrible truth, and then I slid back into a blackout.’

When the affair began, John was married to his third wife, model Genevieve ­Waïte. Mackenzie Phillips, a product of John Phillips first marriage to Susan Adams, was a heavy drug user at the time the affair began. By that time she was then a star in her own right, starring on the hit TV show “One Day at a Time.”

Substance abuse problems led to her firing from the show and went on to tour with her father when he formed the New Mamas and the Papas. By that point in her life, she was a willing participant in their relationship. ‘One night Dad said, “We could just run away to a country where no one would look down on us. There are countries where this is an accepted practice. Maybe Fiji.’ He was completely delusional. No, I thought, we’re going to hell for this.”

Bijou and Mackenzie

Sister Chynna Phillips, 41, told US Weekly how she remembers getting the call from Mackenzie, 49, in 1997 – 11 years after the affair had ended – while she was between flights at LaGuardia Airport in New York City. “She said, ‘I don’t know why, but I just really felt the need to call you and tell you something that I think you need to know. And she went on to tell me that she had had an incestuous relationship with our dad for about 10 years.”

In an interview with Oprah Winfrey airing Wednesday, Phillips also reveals the bombshell that it was her father who introduced her to the drug abuse she’s battled for more than half her life. “My father shot me up for the first time,” she says in a promotional video for the Oprah appearance. “I remember going into my room, I was crouched on the floor. … He put the needle in my arm and put the plunger in and he missed,” she says. “He missed the vein and my whole arm went numb.”

Mackenzie on stage with John

The book also reveals how Rolling Stones singer Mick Jagger tried to seduce her. “Mick Jagger locks the door and he says, ‘I’ve been waiting for this since you were 10 years old,’” she says in the Oprah Winfrey promo, but does not state how old she was at the time.

John Phillips left behind four other children including Chynna, who featured in the singing group Wilson Phillips and Bijou, a model, actress and Hollywood socialite.