“Even though I have been so open about things that I’ve gone through in my life, I’ve never been open about them in an emotional way,” she said. “You know,” and here she started rattling off nightmares like she was listing what to pack for a vacation, “I’ve been sexually abused, bullied, heartbroken, manipulated,” adding divorce — her parents’ and her own — and her father’s cancer to the mix. (Joe Simpson, 61, is also her former manager; after a remission, his cancer recently returned.)

Ms. Simpson writes that for six years, starting when she was 6 years old, she was sexually abused by a daughter of a family friend (who, Ms. Simpson later finds out, was being molested by an older boy). They shared a bed when the Simpsons visited, which was about three times a year. When Jessica told her parents what was happening, they never returned.

“It took me until I was 13 years old to know that if I wasn’t put in that situation anymore, it could stop,” she said. “That’s why I opened up about it in the book, because I really want people to know at a young age, if they are going through that, just speak up earlier because it could have stopped for me so much earlier.”

Sobriety has helped her start to process it all. “I was like: ‘If this is a crutch that’s keeping me from being my best self,’” she said, referring to alcohol, “‘I have to get rid of it and find what’s keeping me from being myself. Why can’t I present myself to the world? Why am I nervous to give myself over to the world when it’s always been so easy?’”

“Even with horrible headlines and fat shaming and you name it, I’ve always been comfortable being open.”

(When I told her that Billie Eilish has said she wears baggy clothes so that no one can comment on her body, Ms. Simpson said: “I’m so happy that there’s somebody out there that talks about that and can do that. I think that is why people gravitate toward her. She’s unique and something new and something fresh and something honest to people. Music’s just not the same as it was when I was in it.”)