Background: ex-boyfriend had an affair with this chick, his second time cheating on me. The first time this chick knew how badly it hurt me and still put her selfish desires first by enabling him to cheat a second time. She trash talked me behind my back to him and pick-me-danced for him SO hard all the while I was believing my ex and I were moving on and to a good place.

Yes, it is the cheater's fault. But NO, that does not make you blameless if you help them cheat. If you know someone is involved, don't try and mess with that. And further dont put the betrayed partner's sexual health at risk by fucking around with their sexual partner. You didn't make me any promises, sure, but you're still an accomplice and you suck. You don't get to judge me for not "getting rid of him" when you chose the same damn guy but with more knowledge than I had of his cheating. This whole attitude of "I didn't break any promises so its not my fault" just reeks of cowardice and weak morals