"He believed in me and made me feel I could do anything," the singer writes of her relationship with Johnny Knoxville

Jessica Simpson is opening up about her past relationship with former costar Johnny Knoxville.

In the singer’s memoir, Open Book — out now — Simpson reveals she formed an intense bond with Knoxville while filming the 2005 film, Dukes of Hazzard.

Although married to Nick Lachey at the time, she admits to having an “emotional affair” with the actor, though the pair never got physical.

“I could share my deepest authentic thoughts with him, and he didn’t roll his eyes at me. He actually liked that I was smart and embraced my vulnerabilities,” Simpson, 39, writes. “He believed in me and made me feel I could do anything.”

The “I Wanna Love You Forever” singer expresses that she “felt a force drawing [us] together” and she “wondered why [she] was open to this.” “Now I was afraid I couldn’t trust myself,” she writes.

The only person in her life at that point who had made her feel that way was, Simpson admits, her father, Joe Simpson. “Certainly not my husband,” she adds of Lachey, 46.

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Jessica Simpson
Jessica Simpson and Johnny Knoxville
| Credit: J. Merritt/FilmMagic

While the two were never physically intimate, it was the emotional bond between Knoxville, 48, and Simpson that, she writes, felt like “betrayal.”

“First off, we were both married, so this wasn’t going to get physical,” she writes. “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.”

She divulges, “Johnny and I had that, which seemed far more of a betrayal to my marriage than sex.”

Simpson and Lachey divorced in 2005 after seven years together and three years of marriage.

nick Lachey Jessica simpson
Nick Lachey and Jessica Simpson

During a recent appearance on The Dr. Oz Show, the star shared there was one thing she would have done differently regarding her divorce.

“I wish I would’ve signed a prenup,” she began. “The funny thing is that Nick wanted me to sign a prenup but I was so offended. I’m like, ‘But we’re going to be together for the rest of our lives. We’re saying our vows to God and in front of all of our family and friends. This is never going to end,’ and we didn’t sign a prenup.”

When Dr. Oz asked the actress and fashion designer what her relationship with her ex is like now, she simply responded: “There is not one.”

Jessica Simpson signs copies of her new book "Open Book" at Barnes & Noble Union Square on February 04, 2020 in New York City.
Jessica Simpson
| Credit: Kevin Mazur/Getty

During Lachey’s Monday appearance on the Today show, he revealed that he has yet to read the book.

“I’ll be honest, I obviously haven’t read the book, so I don’t know what she said or what she revealed there, but I’m certainly happy for her and her life, I know she is happy for us,” the 98 Degrees band member said.

“There’s definitely a mutual respect there, so that’s, you know — obviously it was a long time ago. We’ve all moved on,” he added sitting alongside his wife Vanessa.