>>18 I have to agree with >>18 here. But anyway, I doubt that your girlfriend's cousin is really as horrible as you say he is. Before you can have people stop judging you and accept you, you need to stop judging them and accept them first. In this thread, you were the first to judge as well as most frequent. Re-read your posts, you'll see.
Anyway, you said you didn't have a problem with this cousin guy, but clearly, you dislike him. You said you tried talking to him, but what was the conversation about? Try confronting this guy again. Everyone has a motive for doing things. No one does something just because they want to be an jerk. He must have a motive. Find out. Don't let things get violent. If he hits you, let him, if that's the only way to have him stop. Chances are, if you lay a finger on him, it will make things so much worse for you. Does he realize what he's doing is hurting your girlfriend? If that doesn't help, you're out of luck. You just have to wait until your girlfriend is mature enough to not let something like that bother her.
If you truly want to put this matter at an end, then you have no choice but to stay calm and think clearly. No one here really cares about your past or what you do or what you look like. You're letting your ego get to you, taking this way too personally.
By the way, please, if you're not gonna use caps or spell things correctly enough for me to decipher, at least put some grammar to good use. You're giving me a hell of a time figuring out what the hell you're trying to say half the time.