John Mayer hasn't read Jessica Simpson's memoir, because he ''lived it''.

The 42-year-old musician was mentioned several times in Jessica's recently publish memoir 'Open Book' as the pair dated for five years after her divorce from Nick Lachey.

And although the tome talks about their ''complex'' on-off romance, John has insisted he hasn't read the book because he already knows what happened during the course of their relationship.

During a game of 'Never Have I Ever' on 'Watch What Happens Live' on Wednesday (01.04.20), John was asked if he'd read the memoir, to which he said: ''I've heard about it. I've heard some bits. But as Pee Wee Herman says in 'Pee Wee's Big Adventure' before the movie of his life is about to play out at the end, he's not watching the movie, and the reason he's not watching the movie, he says, 'I don't have to watch it, Dottie, I lived it.' And I think that's prescient here.''

In the book, Jessica claims John was ''obsessed'' with her ''sexually and emotionally'', and said that although they had an instant connection, she often felt insecure about whether she was ''smart enough'' for him.

She wrote: ''I constantly worried that I wasn't smart enough for him. He was so clever and treated conversation like a friendly competition that he had to win.

''My anxiety would spike and I would pour another drink. It was the start of me relying on alcohol to mask my nerves.''

The 39-year-old singer-and-actress also spoke about her relationship with the 'Gravity' hitmaker after the release of her book, and said she ''went back'' to him ''close to nine times''.

She said: ''We were great at intimacy. We were great at loving each other.

''That was easy, but the relationship was very complex.

''It was always on again, off again, on again, off again.

''I went back close to nine times.''

The pair's relationship ended when John dubbed her ''sexual napalm'' in a 2010 Playboy interview.