Arnold Schwarzenegger is back. And he's a little emotional. For the first time ever, Schwarzenegger is finally ready to open up about the scandal that ended his marriage.

"I think it was the stupidest thing I've done in the whole relationship," Scharzenegger tells "60 Minutes" in an interview airing Sunday Sept. 30 on CBS. "It was terrible. I inflicted tremendous pain on Maria and unbelievable pain on the kids."

In 2011 Schwarzenegger and his wife, Maria Shriver, separated after being married 25 years. A week earlier, it was reported that Schwarzenegger had fathered a child with his and Shriver's longtime housekeeper, Mildred Baena.

The interview comes just one day before the release of Schwarzenegger's explosive tell-all memoir, "Total Recall: My Unbelievably True Life Story."

The 65-year-old action star writes that Shriver confronted him during a marriage counseling session a day after he finished his term as California governor in January 2011.

"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 [Baena],'" Schwarzenegger writes in the book about the moment he was forced to reveal that he had a son - Joseph, who turns 15 next week.

Schwarzenegger told "60 Minutes" that Shriver has not read the book, which chronicles his rise from a poor childhood in Austria to the governor's mansion.

"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," he says.

In a preview clip of the interview, Lesley Stahl points out what Shriver sacrificed for the star. "She gave up her television career for you. I mean, wow! Was this just the most unbelievable act of betrayal to Maria?"

Shriver did not comment to "60 Minutes" about the interview or the book.

The former governor of California has largely kept quiet about his affair with the family housekeeper that resulted in a love child whose existence was kept secret until last year. The revelation ended up costing Schwarzenegger his 25-year marriage to Shriver and severely damaged his image.

According to the publisher, Simon & Schuster, in the book Schwarzenegger traces his journey from his small hometown of Thal, Austria, where he was born in 1947, to Los Angeles, where he moved at the age of 21. He tells how he became "the strongest and most muscular man in the world," as he says in the book trailer, and then kept climbing his unique ladder toward "the American Dream."

"No one would believe my life if it were a movie," Schwarzenegger, says in the book's trailer. No kidding. He started his career as a body builder, became Hollywood's biggest star, and, later, was elected governor of California. He's like Oliver Twist ... if Oliver Twist had millions of dollars, pecs, a sub-machine gun, and a stern but practical approach to fiscal reform.

Schwarzenegger is proud of his accomplishments and honest about his regrets, says the book's publisher.

Until the book comes out, Schwarzenegger has launched a competition to win a personalized Arnold message to coincide with the release of his autobiography.

"From today until the release of my book, 'Total Recall: My Unbelievably True Life Story', if you complete this form, I will draw one of you at random each week and send you a personalized audio file," Schwarzenegger says on his website.

He has already uploaded a video of himself recording a "Predator"-themed message for the first lucky winner, Tyler Bates. Sadly, he doesn't say "I'll be back".

On "CBS This Morning," Stahl gave her opinion of why the "Expendables" star went public: "He's trying to get a fourth act. He's the body builder, the actor, the politician. He's working on what's next . I think when he started writing the book he thought this would help whatever is next. And then the scandal became public. He was basically forced to write about it."

"Total Recall: My Unbelievably True Life Story" is available on Oct. 1.