Martha Stewart broke down when she learned that her ex-husband Andrew Stewart cheated on her while they were still married.

The Netflix documentary “Martha” focuses on the respective affairs that Martha, 83, and Andrew had at the time, including how Martha dealt with her then-husband’s infidelity.

Famous Housewife friend Kathy Tatlock explained in the documentary how Andrew cheated on Martha with her former assistant Robyn Fairclough.

“There were rumors that Andy had some connection to the girl who did the flower arrangements at Turkey Hill Farm,” Tatlock said, referring to the Stewarts’ home in Westport, Connecticut.

“Martha noticed everything and became more and more angry,” recalls Tatlock. “She would be beside herself. Migraines and insomnia. At some point she showed me where she had pulled her hair out of her head. She was mean to her employees.”

“She had lost control of Andy,” Martha’s pal added, “so she made everyone pay for it.”

Martha told producers that she let Fairclough live in an apartment on her Turkey Hill Farm.

“When I was traveling, Andy started dating her,” Martha claimed. “It was like I was putting out a snack for Andy.”

The former Martha Stewart Show host confirmed that she confronted Fairclough and “immediately kicked her out” after learning about the affair.

“You know, ‘What the hell are you doing?'” Martha said, adding, “Andy cheated on me, right on our property. Not nice.”

“It’s difficult for me personally to talk about it,” said the star chef about her ex-husband’s affair. “Some people wallow in this self-pity. I just don’t do it. I handed over letters that were very personal. So, guess what – take it out of the letters.”

In the letters Martha gave to producers she wrote: “Dearest Andy. I can’t sleep. I can’t eat. My skin is worried and many lines that weren’t there before are now there. I’m terribly jealous of your other women. I can’t stand the thought of you transferring what we did together to others.”

“I’m in a really fragile, fragile state right now,” Martha also wrote. “All of this makes me feel really physically sick – like my brain is going to break.”

Martha claimed in the document that Andrew was “the one who wanted the divorce, not me.” The exes were married from 1961 to 1990 and have one child, daughter Alexis Stewart, 59.

“He threw me away,” Martha said. “I was 40 years old. I was great. You know, I was a desirable woman. But he treated me like a castaway. He treated me really badly. And in return I guess I treated him badly.”

As for Martha’s own infidelity, she admitted to having a “very brief affair” with a “very attractive Irishman” in the late 1960s.

“It was nothing,” she said. “I would never have broken up a marriage for that.”

Martha thought Andrew never knew about their affair – but director RJ Cutler told her otherwise.

“He says he didn’t walk away from the marriage until you told him you already walked away from the marriage,” Cutler told Martha.

“Oh, that’s not true. “I don’t think so,” Martha replied.

Martha met Andrew on a blind date when he was 23 and a Yale law student.

After their divorce, Andrew married Fairclough. The two eventually divorced.

Andrew later remarried in 2016 to Shyla Nelson Stewart, the president and CEO of Fieldstone Publishing.

Andrew is reportedly “furious” over his ex-wife’s confession to the doctor about their own affair.

The post has reached out to Andrew for comment.

“Martha” is streaming on Netflix.