Arnold Schwarzenegger has confirmed he had a "hot affair" with actress Brigitte Nielsen at a time when he and Maria Shriver were dating and already living together.
Schwarzenegger and Nielsen co-starred in the 1985 film Red Sonja.
Nielsen wrote in a memoir published last year that she and Schwarzenegger had an "outrageous affair" while making the movie and that she did know until later that he was involved 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 indeed have a "hot affair", but he knew it would not last. In fact, their "fling" only made him realise that he wanted to marry Shriver. Nielsen would soon marry Schwarzenegger's fellow action star, Sylvester Stallone.
He also writes that Shriver was criticised by her mother for trying to persuade him against running for Governor of California in 2003 - a confrontation which ultimately 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 stopped his ambitions.
The Terminator and Total Recall star says in the book that he had decided against running in a recall election to remove governor Gray Davis after his wife implored 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 thwart 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 at the time, but learned of it later.
Maria Shriver then softened her stance, paving the way for Schwarzenegger to announce his candidacy on The Tonight Show with Jay Leno, where he says he felt most comfortable.