Jessica Simpson was "killing [herself]" with drugs and alcohol when trying to block out the pain of being abused as a child.
The 39-year-old star was warned by doctors that her self-medication was endangering her life and so she's now been sober since November 2017.
In an excerpt from her new memoir, 'Open Book', obtained by People magazine, she admitted: "I was killing myself with all the drinking and pills.
"Giving up the alcohol was easy. I was mad at that bottle. At how it allowed me to stay complacent and numb."
But while giving up the booze was "easy", the 'Dukes of Hazzard' star admitted therapy was much more difficult.
She wrote: "With work, I allowed myself to feel the traumas I'd been through."
Jessica claimed she was first abused when she was six years old and "shared a bed with the daughter of a family friend."
She admitted: "It would start with tickling my back and then go into things that were extremely uncomfortable."
The 'These Boots Are Made for Walking' singer was desperate to confide in someone but felt frozen with fear and convinced she was to blame.
She wrote: "I wanted to tell my parents. I was the victim but somehow I felt in the wrong."
Jessica eventually opened up to her parents, Tina and Joe Simpson, when they were in the car when she was just 12 years old and discovered her mother had had some suspicions.
She recalled how Tina slapped Joe's arm and shouted: "I told you something was happening."
Sadly, Jessica's confession was never discussed again.
She wrote: "Dad kept his eye on the road and said nothing. We never stayed at my parents' friends house again but we also didn't talk about what I had said."
Jessica - who has kids Maxwell, seven, Ace, six, and 10-month-old Birdie with husband Eric Johnson - recalled how she hit rock bottom after a Halloween party at her house in 2017.
She told her closest friends: "I need to stop. Something's got to stop. And if it's the alcohol that's doing this, and making things worse, then I quit."
The star has been sober since that day thanks to the support of her friends, parents and family, as well as a team of doctors and two therapy sessions a week and admitted her newfound clarity is a "continual gift".
She said: "When I finally said I needed help, it was like I was that little girl that found her calling again in life.
"I found direction and that was to walk straight ahead with no fear.
"Honesty is hard but it's the most rewarding thing we have. And getting to the other side of fear is beautiful."