"I'll be honest, I obviously haven't read the book, so I don't know what she said or what she revealed there," Lachey said. "But certainly happy for her in her life and I know she is happy for us. There is definitely a mutual respect there."
"Obviously it was a long time ago and we've all moved on," he added of his current wife and Simpson's husband, Eric Johnson.
In a previous interview with People, Simpson spoke out about her tumultuous relationship with Lachey, which was documented on their reality show, Newlyweds: Nick & Jessica, from 2003 to 2005.
"We were young and pioneering our way through reality television, always miced and always on," she said. "We worked and we were great at it but when it came time to being alone, we weren’t great at it anymore."
Now, though, Simpson said she has no hard feelings toward Lachey.
"I respect Nick very much. I was really young and my success hadn’t really begun," she said. "He knew me as this young innocent 18-year-old that had never been introduced to the world in so many ways. I went straight from my father to him. Nick’s very smart. He was eight years older than me, but he was also young."
"We meant a lot to each other and we always will," she added. "I want to be very respectful because I married him for a reason and we were together for seven years for a reason. He has a family now and I would never say anything to disrespect that."