Arnold Schwarzenegger told Maria Shriver her mother was "out of control" after learning that she was looking into his bedroom affairs.

The 65-year-old actor speaks about his mother-in-law Eunice Shriver in his new memoir Total Recall: My Unbelievably True Life Story. Arnold reveals some very personal stories in the tome, including how Eunice meddled in his and estranged wife Maria's marital affairs.

The Terminator star and former bodybuilder approached Maria after finding out that Eunice had doctors send her research on steroids to explain why he hadn't gotten her daughter pregnant.

"I just happened to see the report on Maria's desk, so I read it, and I was laughing my head off," he recounts in the tome, before telling his wife: "Your mother is out of control."

The couple went on to have four children together.

Last year it was announced that Arnold had separated from wife of 25 years Maria, after he admitted fathering a child with his household employee Mildred Baena.

Arnold speaks about the secret relationship with his housekeeper in the explosive book which hits shelves next month.

The star says his estranged wife Maria had long suspected he was unfaithful.

"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,'" he writes. "I told the therapist, It's true."