Jessica Simpson didn’t hold back while writing about ex-husband Nick Lachey in her new memoir, Open Book, but he certainly wasn’t the only ex she put on blast.

Following her split from Lachey in 2005, the “With You” singer started seeing John Mayer.

“I would get up to go to the bathroom, and John would ask, ‘Where are you going?’ While I was married, my ex-husband couldn’t be bothered to figure out what city I was in,” she wrote in the book, which was released on Tuesday, February 4. “It felt safe to be desired. I know John would never cheat on me, and that confidence was a new feeling for me.”

While Simpson and Mayer had a sexual connection, their on-again, off-again relationship took an emotional toll on the fashion designer. She eventually moved on from the Grammy winner with NFL player Tony Romo, but Mayer made his way back into her life, ruining her shot at a proposal from the quarterback.

Simpson, who went on to marry Eric Johnson in 2014, also got candid about her battle with substance abuse for the first time in the book.

“I had to strip away all the self-medicating to feel the pain and figure out what was wrong,” she wrote in the introduction. “I’m still doing the work in therapy two times a week resolving those issues.”

While Simpson doesn’t know if she plans to be sober for the rest of her life, she is focusing on the now.

“With this book, I want the freedom to say, ‘Well, there are no more secrets,’” she wrote. “I have grown into myself and come to a place where I want to be honest about my flaws. If I can do that in front of the world, then I can remain honest with myself.”

For details of Simpson’s marriage and divorce from Lachey, head over to Us Weekly’s second Open Book takeaways gallery. Or scroll through for the bombshell revelations about Mayer, Romo and more: