"Because we had brought a third party into our relationship, Ashton said, that blurred the lines and, to some extent, justified what he'd done," she continued.
The couple divorced in 2013 following rumours Kutcher had cheated on her - information which Moore claims she received on the couple's sixth wedding anniversary via Google alert.
"I felt sick to my stomach," she explains.
Radar Online also revealed details about Moore and Kutcher's trip to Mexico. And in a bid to impress her much younger beau, Moore is said to admit to drinking a beer from the mini bar - which ultimately ended her 20-years of sobriety.
"Drinking became interwoven in my pain," she writes.
In her book, Moore also reportedly writes about balancing her career, raising her daughters and her relationship with ex-husband Bruce Willis.
"Such a long time coming," Moore captioned a photo of the first hard copies of her memoir on Instagram.
