Jessica Simpson had secret romance with 'massive movie star' who was already in a relationship

Jessica Simpson detailed her 'hot' romance with 'a world-famous actor' in her memoir.

The Employee of the Month star opened up about the romantic side of her life in Amazon Original Story Movie Star: They Always Say They're Single and one particular romance in particular.

The short - 'and true' - story sees Simpson open up about her love life during the period 2006 after her marriage to Nick Lachey ended.

The synopsis of the book notes it was a time where Simpson 'wonder[ed] who she really [was]' beginning to 'explor[e] what she truly wants in a relationship'.

And who should she end up dating, but a 'world-famous actor' who was her 'A-list childhood crush'.

In the book, Simpson recalls being 'eyeballed up and down' by the mystery A-lister at the 2001 MTV Video Music Awards.

However, it wasn't until after her divorce that she saw the celeb again.

Simpson doesn't name the big movie star. (MEGA/GC Images)

Recalling their first encounter, Simpson said: "This megastar, who I grew up thinking was so hot, eyeballed me up and down. Like he was undressing me with his eyes."

After her marriage was officially over, she allegedly bumped into the movie star again at the Beverly Hills Hotel in 2006, where the two stars shared a kiss.

"I felt this warm rush all the way down my body to the tips of my toes in my wedges," Simpson said.

However, the situation soon flipped on its head as The Dukes of Hazzard star discovered that her secret fling was already in a relationship and had a girlfriend.

She is now married to Eric Johnson. (Instagram/@jessicasimpson)

After witnessing the unnamed actor attend the red carpet with his girl, Simpson realised she 'was never ever in a million years going to be the other woman'.

She alleges the actor told her: "You’re the only girl I want to be with, you’re it."

But Simpson said: "Yes, there was something sexy and enticing about all this, but there was also something demeaning about it. I felt like a call girl."

She realised he was 'hiding me from his chick' and thought: "I didn’t care if he was my teenage fantasy come to life, this was not a choice that same girl, my younger self, would be proud of."

Simpson and Johnson have three kids together. (Instagram/@jessicasimpson)

Sadly this mystery man has not been named, but I'm sure social media will have a thing or two to say about the situation as the rumour mill grinds into action.

Simpson is now married to NFL player Eric Johnson since 2014 and the pair have three kids together.

Movie Star: They Always Say They're Single is available now via audiobook or kindle on Amazon.