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She Discovered That Her Husband Has Been Hooking Up With Her Brother’s Wife On Christmas Morning

profile Emily Chan | Jan 7, 2026
Jan 7, 2026
Portrait of a winter woman in christmas
bakharev - stock.adobe.com - illustrative purposes only, not the actual person

On Christmas morning, TikToker Katelyn Forrester (@mst3katelyn) found out that her current husband is hooking up with her sister-in-law, aka her brother’s wife. Previously, she had a good relationship with her sister-in-law, but clearly that has changed.

“I honestly really loved her,” said Katelyn. “For a long time, I thought she was so good for my brother. I felt like my brother became a better person when he was dating her.”

I praised the hell out of her. I told her all the time I loved having her in my life. I loved her being my sister.”

By the time Katelyn and her husband started dating, her brother and sister-in-law were already married. They always hung out together as couples and had game nights together.

Katelyn had made the effort to include her sister-in-law in every event because she is not the most social person. But come to find out, she has apparently hated Katelyn for years because of this.

Katelyn’s brother and her sister-in-law started having problems in their marriage. She acknowledges that her brother has never been the best husband, but her sister-in-law was no saint either. During this time, she spewed a lot of hate toward Katelyn and her family. They ended up separating, but not divorcing.

Katelyn’s husband and her sister-in-law began bonding on the internet. They constantly played games together online. Katelyn understood that she probably needed a friend, but it was odd that her husband had taken on that role.

“I let him know it made me uncomfortable because she doesn’t like me, and she’s not part of our family anymore, so it’s weird, but he insisted she needs his friendship,” said Katelyn.

She decided to trust her husband because he had never given her any reason not to. She just thought that he was a little too nice and was unable to be mean to people.

Portrait of a winter woman in christmas eve on background of a christmas tree
bakharev – stock.adobe.com – illustrative purposes only, not the actual person

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Eventually, she and her husband moved from central Florida to Los Angeles because she wanted to pursue acting. He wanted a fresh start and was excited about living in a new city—or so it seemed.

One day, he told her that he wanted to do a Dungeons & Dragons campaign with her brother’s soon-to-be ex-wife, but she couldn’t afford the sessions, so he would be paying for her.

It cost $50 a week. Katelyn did not like this idea at all, especially since he rarely took her out on dates or spent any money on her.

Four months later, he told her that he wasn’t happy, and they were not in love anymore. They decided to work on their marriage and bring the spark back, so they planned to go on a date to the movies.

But a few days before the date, he declared that what he really needed was to work on himself. He wanted to go back to Florida to have more support from friends and family.

After spending less than two days in Florida, he called her up, saying that he saw no future with her and wanted to end their marriage. Katelyn was devastated because she had not seen this coming. Another few days later, he backtracked, saying that his decision was a little hasty.

He booked a ticket to fly back to Los Angeles without telling her, even though she had said she wanted some space to process everything. When she told her she was uncomfortable with that, he canceled the flight.

She thought there might finally be some progress in their marriage, but they ended up getting into a fight. Suddenly, her not wanting to have kids was a dealbreaker for him, even though he had always said he was okay with it. He also wanted to take one of the cats, but Katelyn refused to let him, especially since he hadn’t been caring for them.

He came to the apartment to pack up his stuff, and they proceeded with their divorce. Katelyn did her best to move on with her life.

On Christmas, her mom noticed a Venmo transaction. Katelyn’s sister-in-law’s father had sent money to Katelyn’s husband. Katelyn was confused because they had never even met before. Katelyn and her family realized almost immediately what was going on.

“This was a big hit for me because it was confirmation of something I suspected,” she said. “But again, I stupidly trusted him when he said no, nothing’s going on with her. I do feel like an idiot in retrospect.”

She confronted her husband. He didn’t give a straight answer, but he knew he had gotten caught. In retaliation, he drained their savings account of money so she wouldn’t be able to pay her rent.

He also refused to tell her how long he had been hooking up with her sister-in-law. Katelyn called her sister-in-law to confront her as well. She wouldn’t spill the details of how they got together either.

In the end, Katelyn believes they deserve each other.

@mst3katelyn

let me tell you the tale of how I found out my husband is hooking up with my sister in law. part 1 #storytime #cheater #divorce #cheating #fyp

? original sound – Katelyn Forrester

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By Emily Chan

Emily Chan is a writer who covers lifestyle and news content. She graduated from Michigan State University with a degree in... More about Emily Chan