A woman on Reddit inadvertently destroyed her sister's engagement by putting her sister's now ex-fiancé's troubled past on blast to their entire family, despite him opening up to her privately.

The woman explained her would-be brother-in-law "comes from a rough background," though "he has always been very polite and charming" and she has always gotten along with him.

"He doesn't talk about his own family or about his upbringing. My sister said it's a painful topic for him so no one ever pushed," she wrote via Reddit.

At a recent family event, the would-be groom got vulnerable and opened up to his would-be sister-in-law in an intimate moment of trust.

"When I went outside for some fresh air I bumped into him. He was emotional and said it was a hard day for him due to negative associations. He ended up offloading some quite shocking things from his past including that he has a history of very serious drug use (including needles) and that he has done sex work and porn (men and women)," she explained in her post.

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He cried on her shoulder as he opened up to her. At first she felt bad, but as the event went on she began to to feel "more and more uncomfortable."

"I still feel bad for him since he clearly regrets it but it's very shocking to find out he has that kind of history and it does make me feel differently about him," she shared, adding that he is clean today.

Eventually, the woman decided to tell her entire family what he had told her, but then she discovered her sister already knew all about her partner's "sketchy past." Naturally, her sister was livid.

"She was angry and said she was fully aware and it doesn't make her think less of him. I know others might disagree but I decided if my sister and future-brother-in-law weren't going to bring it up then it was my responsibility to make sure my family had the information they needed to make an informed choice about what kind of relationship they have with him," she wrote.

"She is now refusing to speak to me altogether because apparently this has affected future-brother-in-law quite badly. They are no longer engaged because 'he thinks he's not good enough for her' and no one in my family has seen him since all of this happened. Obviously that wasn't my intention and no one said 'he isn't good enough,'" the woman continued, doubling down that she doesn't think she did anything wrong.

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In the comments section, Reddit users roasted the woman for betraying the man's trust, humiliating him for his past and interfering with her sister's engagement.

"You are my worst nightmare—everything I pray my friends and family are not. The deepest circle of Hell is reserved for the treacherous. This man cried on your shoulder and told you his deepest secrets. You then proceeded to gossip like a callous, shortsighted, middle school snotball. Good job screwing over your familial relationships, possibly forever. If I were your sister, I'd never trust you again. If you want even a microscopic hope of unscrewing yourself, you need to apologize right away," one person slammed the woman.

"I could see telling your sister, realizing she knew, and shutting up. But... what was the point in gossiping this painful information to your whole family? Do you have any hard things from your past that your husband told his WHOLE family about so 'they could make an informed decision' about you? You definitely suck. You need to apologize to this guy and your sister. I don't think they'll ever forgive you, but you need to. If they get married, be prepared to not be at the wedding. Be prepared to never be an aunt to their kids. Be prepared for them to miss every family event you go to. You ruined this whole relationship," someone else commented.

"Be sure to tell everyone you meet in future what you did here so they can make an informed decision about you," another wrote.

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