For Arnold Schwarzenegger, promoting his new autobiography, “Total Recall: My Unbelievably True Life Story,” means finally opening up about his affair with his family’s housekeeper.

The tryst resulted in the birth of Schwarzenegger’s now teenage son and, eventually, the end of his 25-year marriage to Maria Shriver.

In an interview with “60 Minutes,” to air on Sunday at 7 p.m. ET/PT, journalist Lesley Stahl asks the former governor of California, “So you lied to [Shriver]?”

“You could say that,” Schwarzenegger responds.

“I think it was the stupidest thing I’ve done in the whole relationship,” he said. “It was terrible. I inflicted tremendous pain on Maria and unbelievable pain on the kids.”

In an excerpt from “Total Recall,” published by ABC, the actor shares the moment that Shriver learned of his infidelity.Shriver apparently made an appointment for the pair with a therapist after Schwarzenegger’s term as governor ended in 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,’” the passage reads. “I told the therapist, ‘It's true.’”

Schwarzenegger’s autobiography will be available on October 1.