“The Terminator” actor writes that Maria Shriver waited until a day after he left the California governor’s office in 2011 to confirm her long-held suspicion that he was a cheater.

“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 in “Total Recall: My Unbelievably True Life Story.”

The 65-year-old action-movie star writes that he initially thought the counseling session was to help him and his wife cope with their transition from public to private life. But once faced with his indiscretion, he came clean.

“I told the therapist, ‘It’s true,’ ” Schwarzenegger recounts in the memoir, set to hit bookstores on Oct. 1.

The Daily News obtained a copy of the book in which Schwarzenegger candidly tells of his journey from a rural town in Austria to becoming a Mr. Universe bodybuilder, Hollywood superstar and powerful politician.

He waits until near the end of the 624-page tome to describe the fling with his married housekeeper Mildred Baena and the secret son he kept from his wife for 15 years.

At first, Schwarzenegger gave Shriver three “lame” reasons why he hid the child, Joseph, from her: embarrassment, a compulsion for secrecy and not wanting her to tell her family — the famed Kennedy clan.

He admitted to Shriver in the Jan. 4, 2011, faceoff that “it was my screwup” and immediately began groveling, telling her she was the “perfect wife” and assuring her that he was still “turned on” by her.

Schwarzenegger confides that he should have told his wife his secret long ago.

“But instead of doing the right thing, I’d just put the truth in a mental compartment and locked it up where I didn’t deal with it every day,” he writes.

He divulges that he had sex with Baena in 1996 in the guesthouse of his Pacific Palisades, Calif., mansion while Shriver was away on vacation with their kids and he was stuck in Hollywood working on the flick “Batman & Robin.”

He writes that he kept Baena on as housekeeper because he thought that was the best way to “control the situation.”

He reveals that many years before the marriage-counseling showdown, Shriver asked him if the child was his, but he adamantly denied it.

Schwarzenegger explains that Shriver implied she had already confronted Baena and learned the truth.

He claims that for a long time he even convinced himself that the boy was not his. But as Joseph grew older, he began to look more and more like Schwarzenegger until the “The Running Man” actor could no longer run from his responsibility.

Fred Prouser/Reuters

Arnold told Maria “It was my screwup” and immediately began groveling, telling her she was the “perfect wife” and assuring her he was still “turned on by her.”

The resemblance was so strong that “I realized there was little doubt that he was my son,” writes Schwarzenegger.

He adds that he was already governor of California when Baena’s husband left her and he began secretly supporting her and her children financially.

Schwarzenegger, who has four children with Shriver, reasons that politically he was doing the right thing by concealing his illegitimate son because he had not campaigned for governor on family values.

“I blocked out the fact that as a husband and father, as a man with a family and wife, I was letting people down,” he writes.

The scandal erupted at a particularly tough time for Shriver, whose mother, Eunice, had just died, and whose father, Sargent Shriver, was battling dementia.

Soon after their marital woes went public, Shriver and Schwarzenegger separated and she filed for divorce.

But she reserved one last public humiliation for him. During her father’s funeral on Jan. 22, 2011, Shriver spoke of how he taught her brothers “to respect women.”

That jibe, Schwarzenegger writes, may have been “partly directed at me.”

Schwarzenegger claims the scandal cost him a role he had eagerly wanted in a movie called “Cry Macho.” But the producer, Al Ruddy, told him the part of a horse trainer’s friendship with a 12-year-old Latino kid hit too close to reality.

He confesses that he has struggled to understand what motivated him to be unfaithful. He writes that his only answer is stupidity — and the arrogance of believing “you’ll get way with ignoring the rules.”

But Schwarzenegger clearly believes in Hollywood endings, adding that he still has hope he and Shriver will get back together.

“You can call this denial,” he writes, “but it’s the way my mind works.”

– NY Daily News