Arnold Schwarzenegger has confirmed he had a "hot affair" with actress Brigitte Nielsen when he and Maria Shriver were dating and already living together.
Schwarzenegger and Nielsen were both in the 1985 film Red Sonja.
Nielsen wrote in a memoir published in 2011 that she and Schwarzenegger had an "outrageous affair" while making the film and that she did know until later that he was having a relationship with Shriver.
In his memoir, Total Recall, My Unbelievably True Life Story, due to be published on Monday, Schwarzenegger writes that he and Nielsen did have a "hot affair", but he knew it was short term. In fact, their "fling" only made him realise that he wanted to marry Shriver.
Nielsen would soon marry Schwarzenegger's fellow action movie star, Sylvester Stallone.
He also writes that Shriver was berated by her mother for trying to urge him against running for Governor of California in 2003 - a confrontation which eventually opened the door to his successful candidacy.
Eunice Shriver told her daughter that her husband would be "angry for the rest of his life" if she halted his ambitions.
The Terminator and Total Recall actor says in the book that he had made the decision not to run in a recall election to remove governor Gray Davis after his wife asked him not to for the sake of their family and Shriver announced his decision to their four children.
But he said that when Shriver told her mother about her efforts to stop his political ambitions, Eunice told her daughter that women in their family "always support the men when they want to do something".
Schwarzenegger said he did not know about the conversation between the two women at the time, but learned about it later.
Maria Shriver then softened her attitude, leading the way for Schwarzenegger to announce his candidacy on The Tonight Show with Jay Leno, where he says he felt most comfortable.
The announcement came after a week of indecisiveness. Schwarzenegger says before he went to the TV studio his wife gave him two pieces of paper with talking points she had written: one in case he decided to run, another in case he decided he did not want to.
Total Recall is part of Schwarzenegger's attempt to rebrand himself after leaving office with a mixed record and subsequent embarrassing revelations about a fling he had with the family's housekeeper which produced a boy, Joseph, who is now around 14.
The actor said he avoided telling his wife about the child for years, even when she asked him, partly because of his long-time desire for secrecy and his fear that the news would become public and undermine his political career.
The former Republican governor also writes about a 2003 White House meeting with Karl Rove in which the top Republican strategist told him the recall election would not happen and instead introduced the actor to then-national security adviser Condoleezza Rice as his pick to run for California governor in 2006.
Schwarzenegger felt overlooked.
He asks: "How could Rove have been so wrong?"
Mr Rove's office did not immediately respond to an email asking for a response to Schwarzenegger's account.
Ms Rice's chief of staff at Stanford University, Georgia Godfrey, said Ms Rice could not recall "any conversation on this subject".