Shannen Doherty says she learned of ex-husband Kurt Iswarienko’s alleged affair shortly before undergoing surgery to remove a brain tumor in January.

“I went into that surgery early in the morning, and I went in after I found out that my marriage was essentially over, that my husband had been carrying on an affair for two years,” Doherty revealed Dec. 6 on the debut episode of her “Let’s Be Clear” podcast.

Doherty, 52, told listeners that Iswarienko wanted to be by her side during the surgery, but she wouldn’t allow it. “I couldn’t go into that surgery with him there. I felt so betrayed,” she explained.

“At the end of the day, I just felt so incredibly unloved by someone I was with for 14 years, by someone that I loved with all my heart,” said Doherty, who filed for divorce from Iswarienko in April after 11 years of marriage.

TODAY.com reached out to Iswarienko for comment but did not immediately hear back.

The former “Beverly Hills, 90210” and “Charmed” star underwent brain surgery in January 2023 to remove breast cancer that had spread to her brain.

Doherty was diagnosed with breast cancer 2015 and went into remission in 2017. In February 2020, she announced that the breast cancer had returned as stage 4 cancer and was “terminal.” In November 2023, she revealed that it had spread to her bones.

Doherty said on her podcast that friends and loved ones, including her mom, supported her during her brain surgery ordeal, which she called “the most frightening thing I have ever been through in my life.”

“I was positive I was going to die,” she said.

Learning of Iswarienko’s alleged cheating made the experience that much more difficult.

“Just to have to go through all of that while trying to figure out if you’re going to get a freaking divorce and trying to get to the truth of that,” she added.

Later in the podcast, Doherty said she became “obsessed” with learning the truth about Iswarienko’s alleged affair, and even spoke to the woman with whom he allegedly cheated.

“If you share 14 years together and you cheated, doesn’t that person deserve the absolute truth regardless of how much that hurts them?” she said.

Doherty said she had always had strict boundaries around infidelity with the men in her life. “I never ever, ever thought in a million years that I would be that girl. I have always said from the beginning, ‘If you cheat on me, you’re out.’ … I’ve been that hardcore about it,” she said.

Yet, Doherty waffled over the decision to end her marriage to Iswarienko, whom she said she previously regarded as her “absolute best friend in the world.”

“I didn’t walk away right away. I couldn’t,” said the star. “I was so confused and I was also on steroids and a lot of stuff from brain surgery because they didn’t want my brain to swell.”

“And honestly, it’s still really hard,” she said. “Yes, I made the decision to file for divorce, but I have a lot of memories with this person.”