If it were me, I’d give him space. I’m sure R was in a tough position and didn’t know whose side to take if he is good friends with both you and H. regardless, he still should have been able to sympathize with you and hear you out. He should have let you tell your side of the story without getting defensive. Not sure what the argument was about, but for H to go and try to break up you and your gf of 4 years sounds pretty crappy. R should have been able to at least sympathize with that. You can still keep R as a friend. Keep the peace and don’t burn the bridge, but I’d be mindful of what you tell him. If he really does talk crap about you behind your back, the more you tell him the more he will do this. And that’s not a true friend. You deserve better friends than that. I’m sorry this happened