Woman says she cut off her sister’s loan help after finding out she’d secretly stayed close to the ex who cheated on her — and the explanation only made the fallout messier

A woman on Reddit said she thought she was dealing with one betrayal when she learned her younger sister had stayed in contact with her ex-husband after his affair. Then she found out it was much bigger than that. In a post later collected by r/BestofRedditorUpdates, she wrote that her ex had cheated on her years earlier, later married the affair partner, and now shared custody of their son with her. She said she recently discovered her 28-year-old sister had not only stayed in touch with him for six years, but had become close friends with his wife — all while hiding it from her. She also said she had been helping that sister pay college loans and decided on the spot to cut her off financially and go no contact.

According to the BORU post, the sister did not initially deny any of it. The woman wrote that when confronted, her sister brushed it off as “not a big deal” and told her she was being petty and still unable to move on from something that happened a long time ago. She said her parents sided with the sister, which only made the split worse. The original post framed the decision pretty bluntly: if the sister wanted to stay close to the man who blew up her marriage and the woman he cheated with, then she could figure out her finances without help.

The update complicated the story in a way many commenters did not expect. The woman said her sister later apologized for how she reacted and admitted she hid the relationship because she knew she would be asked to choose. But she also said there was a reason she had stayed close to the ex and his wife: during a period when she was seriously ill and thought she might die, those two had allegedly been the people showing up for appointments, bringing food, helping with prescriptions, and staying with her, while the woman posting said she did not come to the hospital. The sister told her she still wanted a relationship, but would not cut them off.

That explanation did not repair anything. The woman wrote that she listened, then told her sister she was free to keep those relationships and she was equally free to walk away. She said the sister also told the ex and his wife about the confrontation, and that they offered to help financially, though the sister reportedly turned that down. The BORU thread marks the story concluded, but not because anyone reconciled. It ended with a clean break and a lot of commenters arguing over whether this was really a story about unresolved cheating trauma or about a family history that was more fractured than the first post let on.

The reason the story stuck with readers is that it did not stay in one obvious moral lane. At first it reads like a simple betrayal: sister secretly sides with cheating ex, gets cut off, and faces consequences. Then the update turns it into something murkier, with illness, absence, money, loyalty, and old family damage all mixed together. By the end, the fight was no longer only about the affair. It was about who showed up when things got ugly, and who never really forgave what came before.

Here’s the original Reddit post.