Before his death in 1991, Michael Landon invited his former Little House on the Prairie costar Karen Grassle to give him a call. “We had such a nice conversation,” Karen, who played his wife Caroline “Ma” Ingalls on the beloved show, tells Closer. “We both chose to let bygones be bygones without actually having the conversation. But that meant so much to me.”

In her new memoir, Bright Lights, Prairie Dust: Reflections on Life, Loss and Love From Little House’s Ma, Karen tells the story of her rise from little-known theater actress to costar of one of the most popular family series on TV. She also reveals, for the first time, how her years on Little House were tainted by sexual harassment and a juvenile vendetta perpetrated by Michael. “It’s difficult when you’re feeling so uncomfortable and you can’t defend yourself because if you do, you know there will be more humiliation,” she explains.

Actress Karen Grassle Says She Learned ‘Forgiveness’ After ‘Awful’ Experience on ‘Little House’ Set

It wasn’t always like that. Karen’s relationship with Michael started off on a good note. “My first impression of him was, ‘Wow, he’s really handsome,’” she remembers. “He was also tremendously charismatic with great energy. And he was very sensitive in the audition reading we did together.” The pair of actors had no trouble slipping into the roles of a married couple. “We worked together very well,” Karen recalls. “People would come up to me and say, ‘Oh, my god, the chemistry between the two of you.’ I didn’t think about that. It was more of something that other people could feel.”

But as the show’s star, producer and often director, Michael had a lot of weight on his shoulders, and it sometimes showed in his quick temper. “He was a very, very hard worker, but he could be quite moody,” Karen remembers. “There was a lot of pressure on him.”

The real trouble began after Little House became a hit and Karen asked for a raise, which was denied. “I was shocked because based on the ratings, our good relationship and what my agent had told me, I thought it was a fait accompli,” she says.

Worse yet, her request turned Michael against her. He began cutting Karen’s scenes and making crude jokes at her expense. “He started this campaign on the set, to try to sort of break me down and diminish my value to the show,” she remembers.

In the nastiest incident, Michael told obscene jokes about the way women’s private parts smell to the crew as they crowded around the bed where he and Karen were shooting. “I think they were intended to humiliate me, because we were trapped there in this tiny room, in this bed with all the men standing around. We couldn’t get out of there between shots because it was so crowded. So there I sat in my little nightie, you know, hearing these filthy jokes. I mean, it was awful, awful, awful,” she says.

It was only years later, as the #MeToo Movement gathered momentum, that Karen was able to put a name to what she had experienced. “I called a friend and asked, ‘Was that sexual harassment?’” says Karen.

Karen remained on Little House through eight seasons and eventually even got a raise. “We had been trained, as girls, to rise above all the bad-boy behavior and be quiet and get on with it. And that was what I did,” she says. Today, she looks back at her time on the show, happy to have made peace with everything that occurred. “The most important thing that I learned was forgiveness,” Karen says. “It frees me of the bad feelings.”

—Reporting by Amanda Champagne-Meadows

For more on this story, pick up the latest issue of Closer magazine, on newsstands now.