Chynna Phillips said she "completely shut down" when sister Mackenzie Phillips told her about the alleged 10-year incestuous relationship with their father, John Phillips, 13 years ago. But now the singer said she hopes her new album and her sister's book bring some "healing" to the world.
"I'm still struggling with it. It's going to be a lifelong journey for me," Chynna Phillips said. "It's a terrible, terrible thing."
Despite stating that she believes her sister, Chynna said she could not vouch for Mackenzie's version of the story in her new book, "High on Arrival."
"I cannot say that everything is just as it is written in the book. Because she admittedly was on drugs. So there's no way for me to be able to corroborate," Chynna said.
The former star of the '70s sitcom "One Day at a Time" said that she was first raped by her father, the late lead singer of the Mamas and the Papas, in a hotel room when she was 18 while passed out after a drug binge.
Although Chynna has known about the alleged relationship for years, Mackenzie did not tell Chynna about her tell-all book until after "the train had already left the station."
"She came up and she told me that she was going to be -- that the book was basically already written," Chynna said. "And that she was going to be writing about the incestuous relationship between she and my father."
Michelle Phillips, Mackenzie's stepmother and a former member of the band the Mamas and Papas, has publicly rebuked Mackenzie's allegations.
Michelle Phillips told the Hollywood Reporter that Mackenzie had "a lot of mental illness" and that "she's had a needle stuck up her arm for 35 years."
"Mackenzie is jealous of her siblings, who have accomplished a lot and did not become drug addicts," Michelle said.
Chynna acknowledged the family conflict but said she would not participate in it.
"There's a lot of animosity there. A lot of resentment," Phillips said. "Because I've always said that resentment is like drinking a ton of poison and waiting for the other person to die."
Since Mackenzie's public confession on Oprah, counselors have seen a jump in people seeking help for abuse and incest.
Between Sept. 22 and Sept. 24 the Rape, Abuse and Incest National Network (RAINN) says its hotline had a 26 percent increase in call volume and their online hotline had an 83 percent spike.
"I hope that my album and her book bring a lot of peace and healing to the world," Phillips added. "That would be a wonderful gift."
Chynna, now a member of the Christian band Chynna and Vaughn, released her new album, "One Reason," the day before her sister's book.
The former Wilson Phillips band member says she loves Christian music because she can combine her faith and her music.
"I get to write prayer to God in my lyrics. And I get to perform in front of people, but it's not performing anymore. It's showing up to worship God and to be able to have other people in the room be there," Phillips said.