So I'm dating my best friends brother and he was my first bf and I his first gf and my bff didn't like it the first time but then we broke up and Now back together a few years later and have been together for 4 months my bff didn't like it but accepted it then she got a bf and she's rarely around and we don't talk much but my bf hates his sister and his other sister alot and my friends bf so he's always a complete asshole to them and I've asked him to knock it off but he just says there annoying and he hates them and he doesn't care and Now my used to be bff texted me tonight telling me that she doesn't understand why hr treats them like crap and it affects her and her bfs relationship and she kept telling me to make him stop and help him and crap and that he didn't treat his sisters like shit with his last 2 gfs but started being an asshole after me and him got together and I just don't know what to do because I know I can't make him change nor would I make him change. But she's also changed after she started dating her bf and she's been acting meaner towards her parents and stuff and I just don't know if I should keep being her friend or not or what I should do anymore. (Sorry this was so long ha)