In one marriage counselling session, the counsellor told Schwarzenegger that his former wife Maria Shriver wanted to know if he “was the father of Joseph”.

Arnold Schwarzenegger thought his “heart stopped” when Maria Shriver confronted him about his love child.

The 76-year-old actor revealed he and former wife Shriver went to couple’s therapy twice, and during one of the sessions, he was questioned about Joseph Baena, the secret son he had with their housekeeper Mildred Baena.

He told the Times newspaper: “The only time I was in therapy was when I went with my wife, when we had a problem with the marriage. I went twice and that was it.”

He explained that in one marriage counselling session, the counsellor told him Shriver wanted to know if he “was the father of Joseph”.

Arnold said: “I thought my heart stopped. And then I told the truth: ‘Yes, Joseph is my son.’

”My world came crashing down around me. I blew up my family. No failure has ever felt worse than that. I did that to myself.

”I had to go to my kids and explain it to them. I am going to have to live with it for the rest of my life. People will remember my successes and they will also remember the failures. And this is a major failure… a whole different dimension of failure.”

Despite the affair, Schwarzenegger - who has Katherine, 33, and Christina, 31, Patrick, 30, and Christopher, 26 with Maria - said he originally had no idea Joseph, 26, was his son.

He said: “In the beginning, I really didn’t know. And the older he got, the more it became clear to me. And, then it was just really a matter of: how do I keep this quiet? How do you keep this a secret?”

Despite the upheaval, Schwarzenegger - who has recently written a self-help book, Be Useful: Seven Rules for Life - and Joseph are now very close, and he and Maria “have a really great relationship”.

He said: “Any kind of special day we have together as a family, and everyone is really happy about that. But it’s not what it was, when we were all together under one roof as a family.

”I hate to do anything by myself. I like to travel with a bunch of people and show off. I’ve always trained with training partners, very rarely alone. When I have lunch or dinner or breakfast, I go with somebody. When I go to the football game, I go with somebody.

”I had three open-heart surgeries. Every time you go under, you don’t know if you’re going to see this world again. That makes you think about things. And then eventually, you get to an age where friends are passing away.”