Arnold Schwarzenegger has confirmed that he had a fling with Brigitte Nielsen while he was dating Maria Shriver. In his new memoir, In Total Recall: My Unbelievably True Life Story, Arnold copped to the relationship -- which Brigitte first wrote about in her book last year.  In Nielsen's memoir, she deemed the fling "an outrageous affair." Arnold stayed silent on the subject at the time, but in his book he says that the relationship with Brigitte made him realize he wanted to marry Maria.  Nielsen married Arnold's friend Sylvester Stallone, but the couple split after 19 months of marriage.  Arnold gave a candid interview to 60 Minutes in support of the book -- and spoke about the affair with the family housekeeper that resulted in a love child and eventually ended his marriage to Maria.  When asked if Maria knew that he'd written about the infidelity, Arnold responded, "She knows that it's about my whole life and that I would not write a book and kind of leave out that part, and make people feel like, well wait a minute, are we just getting a book about his success stories and not talk about his failures? And that's not the book I wanted to write. I wanted to write a book about me: here's my life."  Arnold then admitted how terribly his actions damaged his family: "I think it was the stupidest thing I've done in the whole relationship. It was terrible. I inflicted tremendous pain on Maria and unbelievable pain on the kids."