Hollywood star Arnold Schwarzenegger has opened up about the affair he had in 1996 - with his housekeeper - while he was still married to Maria Shriver.

The actor, 75, is set to "tell his own life story" in the upcoming three-part docuseries 'Arnold', which is scheduled to be released on June 7, reports Mirror.co.uk.

And now it has been revealed that in the tell-all docuseries, Arnold will recall the moment Maria confronted him about the affair. In 1996, Arnold had an affair with housekeeper Mildred Baena, who fell pregnant and welcomed a child nine months later, which happened to be just five days after Maria and Arnold's son Christopher was born.

Mirror.co.uk further states that at the time, nobody knew that Mildred's son was actually Arnold's child, or that Christopher was his half-brother.

But as Mildred's son Joseph grew up, she noticed that he looked a lot like the famous actor she had an affair with months prior to welcoming her son.

It wasn't until 2010 when Joseph was 13 that he learned who his biological dad was, which came when the media announced it. Arnold has now spoken about the affair and how his "heart stopped" when Maria confronted him about the affair in a counselling session, as per US Sun.

"One day, the counsellor said, 'Today Maria wants to be very specific about something. She wants to know if you're the father of Joseph'."

"I thought my heart stopped. And then I told the truth," he says in the new docu-series.

He then went on to reveal how he was honest, admitted that Joseph was his son and that Maria was "obviously crushed by that."

Speaking about his son Joe in the docuseries, Arnold added: "In the beginning, I really didn't know, but the older he got, the more it became clear to me. It was then just a matter of, 'How do you keep this quiet?'"

Arnold then admits that the affair he had with the housekeeper was his biggest "failure", adding that he has "caused enough pain" for his family and noting how "everyone had to suffer."

"Maria had to suffer, the kids had to suffer, Joseph, his mother, everyone. I'm going to have to live with that for the rest of my life," he added.