Boyfriend's Bad Friend.?

Dump him. He seems like the kind of guy who would cheat on you. Of course he isn't going to admit that but since he was getting all defensive when confonting him, it tells me right there that he would have no problem going out with his friend and cheating on you. If you can keep him away from him do it, but otherwise it seems like he would easily fall under the pressure of his friends cheating ways.