My now ex boyfriend and I dated for 3+ years and broke up a little over 4 months ago. He cheated on me throughout the whole relationship and never really treated me great. He was always weirdly close with my sister and they would always text/Snapchat each other. When we were dating I thought nothing of it, just enjoyed the fact that my boyfriend got along so great with my family. I was at my sisters house last weekend and we were all drunk and she let it slip that she has started sleeping with my ex. I freaked out and called her all sorts of names and basically told her to never talk to me again. She talked to my mom and told her what was going and now my mom is saying I’m being dramatic and that I should let it go. If it was just a one time deal I could MAYBE let it go, but she’s slept with him at least a handful of times. This man broke and walked all over my heart and now that he’s with my sister it’s even worse. Would you be pissed if your sister slept with your ex??