can’t even trust your own family OR man

I NEVER FELT SO BETRAYED IN MY ENTIRE LIFE. I honestly don’t know how to feel about this situation.. I’m so hurt and heartbroken. I really didn’t deserve this at all.. so last saturday was my bf’s birthday and so we spent the whole day together & then he went out with his friends later that night.. so after that he came over and we had sex.. a few days later i tend to find out he’s been messing around with other girls and ONE OF THEM IS MY OWN COUSIN LMAOOO. WTF she blocked me on everything and she posted him on her private “finsta” instagram account and captioned an old picture of them from high school saying “just cuz it’s my boos birthday” lmao how fucken disgusting. What’s more disgusting is that that claimed to be cousins ! I honestly don’t know how to feel, he did me so wrong and now he’s making it seem like I’m the bad person here. I confronted him about it too and all he told me was to kick rocks. Lmao I did so much for this guy, helped him out with so much and even money wise too. My heart was already broken from personal issues but this just broke it even more💔😞