Actor Arnold Schwarzenegger lied to now-estranged wife Maria Shriver about his affair with their housekeeper years before it became public because he was "too scared" of losing his family.

The action man-turned-politician stunned Hollywood last May (11) when he separated from the mother of his four kids after 25 years of marriage and then admitted to fathering a son with maid Mildred Baena, who worked at the pair's home.

Schwarzenegger, who is currently in the middle of divorce proceedings, confessed to the indiscretion in couple's therapy, the day after stepping down as California governor, but now The Terminator star reveals he not only hid the news from a suspicious Shriver, he also denied the allegations to her face more than once in a bid to keep his family together.

During an interview on U.S. breakfast TV show Good Morning America on Monday (01Oct12), he said, "I just did not know how to (tell her). I was just, I think, too scared to lose everything, losing her, losing the family, and I just didn't know how."

The 65 year old now regrets not telling Shriver sooner, insisting, "It's easy to be smart in hindsight".

He also admits he kept Baena employed at their home so as not to punish her for his mistake, but wishes he could take it all back.

Schwarzenegger adds, "It's worse when you start getting rid of people, because it's kind of like punishing somebody for having been in the situation... When you look at the whole thing it was just so horrible, what it did to the kids and what it did to my wife, because they were really fantastic. I had the most extraordinary family that anyone can ever dream of."