Arnold Schwarzenegger: Affair With Housekeeper Mildred Baena Was 'Stupidest Thing I've Done' to Maria Shriver

Arnold Schwarzenegger knows he made a major mistake.

In an interview with "60 Minutes" airing Sept. 30, the former Republican governor of California, 65, speaks candidly about his extramarital affair with housekeeper Mildred Baena that resulted in the birth of his fifth child, Joseph, 14. (The shocking news of Schwarzenegger's infidelity and secret son was not revealed until May 2011.)

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Reporter Lesley Stahl reminds Schwarzenegger that his wife of 25 years, Maria Shriver, "gave up her television career" to support his dreams. "I mean, wow! Was this just the most unbelievable act of betrayal to Maria?"

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"I think it was the stupidest thing I've done in the whole relationship," the "Terminator" actor replies. "It was terrible. I inflicted tremendous pain on Maria and unbelievable pain on the kids." (Schwarzenegger and Shriver, 56, are parents to Katherine, 22, Christina, 21, Patrick, 19, and Christopher, 15.)

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Schwarzenegger appears on the program to promote his new autobiography, "Total Recall: My Unbelievably True Life Story." In recently released excerpts from the memoir, the ex-bodybuilder admits he did not confess to fathering a child with Baena until a Jan. 4, 2011 couples' counseling session. "The minute we sat down, the therapist turned to me and said, 'Maria wanted to come here today and to ask about a child -- whether you fathered a child with your housekeeper Mildred,'" Schwarzenegger writes. "I told the therapist, 'It's true.'"

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Shriver waited to confront Schwarzenegger about his affair until after his term as governor had ended. When she did, the politician begged his wife to forgive him, admitting he "screwed up." They announced their separation on May 9, 2011, but Schwarzenegger still hopes to reconcile with the activist and author. "You can call this denial," he writes. "But it's the way my mind works."

"60 Minutes" airs Sunday, September 30, at 7 p.m. EST on CBS.

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