Alison Arngrim was 12 years old when she landed the role of Nellie Oleson, the iconic golden-haired villain on "Little House on the Prairie." Her character was known for her brazen attitude and fearlessness, but off camera, Arngrim says she was hiding a painful secret. On a new episode of "Oprah: Where Are They Now?" she opened up about the sexual abuse she suffered as a child.
"So here I was playing this girl that everyone was afraid of and it's great," Arngrim says in the above video. "I'm paid to play this person who screams, yells, throw things, vents her anger, just lets it out, doesn't care who's looking, shows all the worst parts, makes terrible faces and doesn't care how awful she looks.
"It was absolutely therapeutic," she says.
Starting at age 6, Arngrim says she was sexually abused by a relative for three years.
"I actually read somewhere the average length of time for someone to come forward about being sexually abused is 14 years from the incident," she says. "I was in my early 20s when I first started talking about it and went to therapy, so I was right on schedule -- textbook."
Because she was so young, Arngrim says she didn't tell anyone when the abuse started. "I wasn't quite completely clear on exactly what it was that was being done to go report this," she says. "So when I started to get older and realize what it was, that's when I actually said 'No, I'm not doing this anymore.' And amazingly, it stopped."
Arngrim says her cast mates never knew about the abuse, and she even kept the secret from her family. "It was awful," she says. "It's keeping the secret is the worst part. It's wondering, can someone tell by looking at you?"
In the below video, Arngrim joins "Oprah: Where Are They Now?" executive producers Jill Van Lokeren and Julie Simpson on HuffPost Live and talks about why she eventually went public about her abuse and her work with the National Association to Protect Children.
"Oprah: Where Are They Now?" airs Sundays at 10 p.m. ET.