WWW- THE already shaky marriage between Jessica Simpson and Nick Lachey is about to hit another big speedbump.

Jessica Jaymes, a porn star who performed raunchy sex acts with another woman in front of Lachey and pals at a bachelor party last year, is trying to sell a story to the tabs about what she claims really happened that night – and it isn’t pretty.

Last year, Star magazine reported in a story where no one was on the record that Lachey and his crew met up with Jaymes and two female friends [“an Asian and a blonde”] at an L.A. club. The crew later went back to a Hollywood Hills home where the women gave a sexual performance, which included “whipped cream and sex toys.” Also with the group was a male friend of Jaymes.

At one point, Lachey got on the bed with the girls and seemed “in a trance.” Eventually, Jaymes’ male pal became “so concerned” about something that Star doesn’t specify, he “intervened,” pulling Jaymes away from the bed – to Lachey’s “dismay.”

Now, we hear, Jaymes and her business manager Gordon Yugovich are asking $1 million plus syndication rights to the “entire story” with steamy details that are sure to make Simpson’s hair stand on end. This time, not only will Jaymes be on the record, but her two girlfriends as well as the man who pulled her from the bed are supposedly going to talk – all confirming Jaymes’ story.

Both Jaymes and Yugovich refused to “confirm or deny” details to PAGE SIX, although both noted something was being shopped around.

We also hear Jaymes is going to shop a book about the incident. But so far, there have been no takers. The deal has gone out to Life & Style and In Touch, as well as Us Weekly, National Enquirer and Star.

Maybe no one is buying because Jaymes has already gone on the record with Howard Stern saying “nothing happened,” according to Lachey’s attorney, Martin Singer. And she told PAGE SIX last year, “Everything’s been exaggerated.”

A rep for AMI said: “The National Enquirer was contacted about a story and isn’t interested” – a sentiment echoed by Us Weekly.

But in an ominous sign, Simpson is no longer repped by Hollywood stalwart Brad Cafarelli, but by Rob Shuter at Dan Klores Communications – known to many as a “crisis management” firm.