When Jessica Simpson titled her 2020 memoir Open Book, she meant it. In it, the singer writes about her relationships with several famous men, including her ex-husband Nick Lachey and ex-boyfriend John Mayer, her experience with alcoholism and journey to sobriety, and her struggles with body image.

Simpson even reveals the details of what she dubs an “emotional affair” with one of her co-stars from the 2005 movie The Dukes of Hazzard. Read on to find out who Simpson got close to and what she had to say about their meaningful connection.

Simpson married fellow pop star Lachey in 2002. Soon, the two had their own MTV reality show about their relationship: Newlyweds: Nick and Jessica. But, their marriage quickly crumbled, and she filed for divorce at the end of 2005.

In the book, Simpson claims that Lachey tried to get her to stay in the marriage even after she filed the paperwork. “He didn’t like me so I didn’t understand what it was he was trying to save,” she writes (via Yahoo!). She says that she told him, “Love is not enough. If love was enough, I would stay forever, but it isn’t enough. We have to like each other.”

Toward the end of 2004, Simpson began filming The Dukes of Hazzard and formed a bond with co-star Johnny Knoxville. At the time, he was married to Melanie Clapp.

Simpson said that she developed feelings for Knoxville, because he supported her and she could be herself around him. She didn’t feel that way about Lachey.

“I could share my deepest authentic thoughts with him, and he didn’t roll his eyes at me,” she writes in Open Book (via People). “He actually liked that I was smart and embraced my vulnerabilities. He believed in me and made me feel I could do anything.”

Simpson explains in her book (via E! News) that when it came to Knoxville, she “felt a force drawing [them] together.” She continues, “I wondered why I was open to this. I was already living in a distrustful situation with Nick, and now I was afraid I couldn’t trust myself.”

But, she says, the connection was purely emotional. “First off, we were both married, so this wasn’t going to get physical,” she shares. “But to me, an emotional affair was worse than a physical one. It’s funny, I know, because I had placed such an emphasis on sex by not having it before marriage. After I actually had sex, I understood that the emotional part was what mattered. Johnny and I had that, which seemed far more of a betrayal to my marriage than sex.”

Simpson and Knoxville stayed in contact via letters after filming on the movie wrapped, according to Simpson.

She writes in Open Book that they were like “prison pen pals” who were being kept apart. “We wrote these flowery love letters back and forth, often at night with Nick passed out in the bed next to me,” she writes (via TooFab). “We talked about music, and I would listen to the Johnny Cash songs he suggested just to feel like we were still together.”

Eventually, she realized she needed to stop communicating with him. “I began to realize contact with him was an addiction, and I would make these grand pronouncements that each time was the last time,” she writes. “I was grateful that he had expanded my worldview and made me appreciate so many things about culture, but I needed to walk away. This wasn’t a game.”

Simpson and Knoxville never actually dated. She married her current husband, former football player Eric Johnson, in 2014. Knoxville and Clapp divorced in 2009, and he went on to marry Naomi Nelson in 2010, though he filed for divorce earlier this year. As for Lachey, he married TV host Vanessa Lachey in 2011.