Jessica Simpson was "saddened beyond belief" when Nick Lachey started dating after their split.

Jessica Simpson

Jessica Simpson

The 40-year-old pop star was married to Nick between 2002 and 2006, and has admitted to being shocked at just how quickly he moved on from their romance with his now-wife Vanessa.

In the paperback edition of her 2020 memoir, 'Open Book' - which includes previously-unseen journal entries - Jessica wrote in an extract shared with 'Entertainment Tonight' : "So, Nick, you're with another already? Seems that you forgot the love you spoke to me. I'm saddened beyond belief. Alone in the dark, with no one to call my own."

Nick, 47, started dating Vanessa less than a year after his split from the Jessica and the pair went on to tie the knot in 2011 and now have kids Camden, eight, Brooklyn, six, and Phoenix, four, together.

In her book, Jessica described Nick as her "first love".

The blonde beauty - who previously admitted to being a virgin before their marriage - wrote: "Nick loved the fact I was so strong in my faith and that I had this wide-eyed innocent approach to life. When he proposed in 2002, I said yes."

Jessica also insisted she remains respectful of her ex-husband.

The singer - who has Maxwell, eight, Ace, seven, and Birdie, two, with her husband, Eric Johnson - said: "I was really young and my success hadn't really begun.

"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. 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."