Angelina Jolie has instructed her lawyers to prevent her former Irish bodyguard from writing an explosive expose.
The star (33) is said to be distraught about news that Mickey Brett is to write a tell-all book revealing intimate details of her courtship with Pitt.
Mr Brett (52) had served as head of security for seven years and headed up the Jolie/Pitt's security detail when the couple went into hiding in Namibia before the birth of baby daughter Shiloh in 2006.
Angelina's trusted confidant was reportedly fired by Pitt (45) in 2007 on charges of assaulting a restaurant owner.
Publishing sources said that there will be allegations that Pitt did cheat on ex-wife Jennifer Anniston (40) while he and Jolie were filming Mr and Mrs Smith.
"Mickey walked in on Brad being intimate with Angelina in her trailer," the source claims. "He [Brett] knows everything about Angelina. It's going to be one of the most explosive books ever written."
The publishing source also said that Jolie won Pitt over by doing whatever he wanted in bed, including "buying sex toys, paddles and whips and dressing up in latex".
Pitt recently attempted to clear up the rumours in an interview after Jolie revealed that the couple had met and fallen in love on the set of action film Mr & Mrs Smith, which was made when the movie hunk was still married.
He insisted there was no "dastardly affair".
And in the latest move, Jolie is attempting to limit the damage which could be caused if the book is published. It is believed that Mr Brett did not sign any confidentiality agreements when he worked for Jolie.