Man says girlfriend of 10 years had secret affair with his brother-in-law. His attempt to live with it came at a high cost: ‘We were all best friends’

A man and his girlfriend had reportedly been together since high school, building a house and raising two daughters near his older sister and her husband. He now claims his girlfriend had a six-month affair with that brother-in-law, according to a post he shared on Reddit by u/SFFEnthusiastPls in r/BoyDinnerDiaries. He says the group had been best friends before the alleged affair came to light.

He says he found evidence of the affair on his girlfriend’s phone in 2023. He reportedly waited until his sister came home from the hospital with her second child before revealing what he knew. His ex apparently admitted to the affair right away, while his brother-in-law allegedly denied it at first and tried to bribe him to stay quiet.

She moved out briefly, and he claims she seemed unbothered until she learned her brother-in-law had no plans to leave his wife. He eventually took her back, and the pair reportedly tried to make it work for nearly two years. According to the Redditor, he admits he lasted that long as he was on antidepressants, sleeping pills, and benzos, along with medical THC and CBD.

Quitting everything at once apparently pushed him into a crisis

He says he finally ended the relationship for good last October, nearly two years after learning about the brother-in-law affair. When he stopped taking all of those substances, he reportedly reached a breaking point and had thoughts of ending his life.

Around half of patients who stop antidepressants may experience withdrawal effects, according to The Pharmaceutical Journal. These effects can reportedly be severe and last for several months. The psychological symptoms may include anxiety, panic attacks, and suicidal thoughts, which could help explain how quickly his situation appears to have escalated. 

According to the Redditor, the episode ended in urgent care alongside his mother, and he moved in with her afterward. The couple sold their house in January, and his ex reportedly took 60% of the sale proceeds. However, the fallout apparently went well beyond money. He says he cut off his sister as she chose to stay with the brother-in-law, and he feels she is not mentally stable.

He also says he hates his father, whom he describes as useless and unhelpful throughout the ordeal. His dog reportedly developed cancer and died during the same stretch. He is now said to be living in a rental with his daughters after spending time at his mother’s and younger sister’s homes.

His focus now appears to be finding a long-term home for himself and his daughters, and a therapist to help them heal. However, he admits he still struggles with his mental health and is trying to quit vaping, which he calls his only remaining vice. “My daughters are strong but they hurt, and I hurt so deeply too,” he wrote.

Commenters appeared largely sympathetic, as cheating within the family tends to draw strong reactions online. One person asked whether his sister had divorced his former friend and brother-in-law, while another wrote, “What a really evil person to do this to family?” A third urged him to spend time with friends who have his back.