Rooney, 90, recently obtained a restraining order against Chris Aber, claiming his stepson emotionally abused him and took control of his finances.
This week, Rooney called upon the Senate Special Committee on Aging in Washington to help end the abuse of elders by their caregivers.
"I'm asking you to stop this elderly abuse. I mean to stop it. Now. Not tomorrow, not next month, but now," he told the commission.
"I can barely speak. My stomach is knots. It hurts me very much," Aber told TV's "Inside Edition" Friday about Rooney's allegations.
Rooney's daughter, Kimmy Rooney, said members of the family thought something was going on but her father was too terrified to tell them.
"I think it's been going on longer than any of us would like to admit," she told "Inside Edition."
Aber said he is devastated his stepsister would think that.
"I love my sister very much," Aber said. "Once this blows over, we'll be friends again."
Mickey Rooney's film credits include "Boys Town," "Babes in Arms," the Andy Hardy film series, "Breakfast at Tiffany's" and "Night at the Museum."
He received a special Academy Award in 1938 and an honorary award in 1982, and was nominated for five acting Oscars. A five-time Emmy nominee, Rooney won an Emmy in 1982 for his performance in "Bill," as a mentally challenged man making his way into the world for the first time.