Mildred Baena said Shriver finally asked her "point blank" whether her son had been fathered by Ahnold.
Baena said she got so emotional that she fell down on her knees in front of her.
“She was so strong. She cried with me and told me to get off my knees. We held each other and I told her it wasn’t Arnie’s fault, that it takes two.”
Baena broke her silence about the scandal in an interview today with Hello! magazine, revealing the name of the 13-year-old love child -- Joseph -- and saying that his reaction when he found out Ahnold was his dad was "Cool!"
Baena said Shriver sensed "something was up" after hearing "whispers" in the household about Joseph's resemblance to Schwarzenegger.
"[Maria] would say things like, 'I’m here if you need to talk.' I sensed something was up. I have so much love and respect for Maria."
Mildred said Joseph is looking forward to building a relationship with Schwarzenegger, who reportedly is in the process of divorcing Shriver.
Baena revealed that she realized the truth once her son started to resemble the former governor.
“It was as Joseph grew and I started to see the resemblance that I wondered – but it became more apparent as time went on,” she said.
“I knew Arnold was the father, and maybe as Joseph got older and began to look like him, he [Arnold] wondered. But he never said anything to me."