So, I've known this guy for a few years and was friends with his ex-girlfriend, whom he cheated on. Fast forward a few years later and he has a different girlfriend - who he also cheated on earlier in the relationship. At the beginning of the summer, she moved away, and he started messaging me - he said that they were now in an open relationship and she didn't care what he did when he wasn't with her. Not that I'm proud, but at first I kind of got swept up in how much attention he was giving me and all the compliments, but I was still hesitant because of his history. He talked about coming to visit me, wanting to be a different person, we both opened up about hurts and insecurities, and I opened up about my traumas, abandonment issues and BPD. I started getting annoyed mostly because all he did was talk about himself and how horrible his life was - I'm pretty sure he also has some cluster B traits as he also needs constant validation from women. I also felt kind of uneasy because whenever I asked about his relationship status, he avoided the question. After about a month and a half of talking and some sexting, he told me he was going to see her and had decided he was probably going to move there. I felt like he'd taken advantage of me and used me as a way to make himself feel better and to pass the time. I eventually kind of cut things off and thought that was that. 

After about a month of not hearing from him, and seeing Instagram photos of them together in BC, it kind of hit me that I didn't think she knew anything about what he was doing. I also realized he probably lied to me. I then got a text from him and all it said was "do me." I got pretty upset because I felt objectified. He kept asking if I wanted to see him naked, and I responded no but he kind of kept pushing the subject. I finally snapped and sent him a lengthy text message calling him out on lying and cheating, etc. I think I may have also been upset about the rejection, but I just got so angry at the idea of some men treating me (and other women) like garbage. So, I took screenshots of some of the messages from the summer and sent them to her. 

The next morning, I woke up to texts from him asking me why I would do such a thing, justifying it by saying he was drunk. He told me I was a monster. I told him I have zero regrets because he lied to her for months, and likely lied to me about his situation, and told him to take responsibility for the consequences of how he treats people. He's cheated on every girlfriend he's ever had, and uses people to boost his own ego. 

I feel completely vindicated and justified with what I did, and I think she deserved to know. But if I'm honest, I also did it out of revenge and to enact some kind of justice, and part of me did want to hurt him back. But I'm not sure, should I feel bad about what I did?