How do i brake a copel up (she is a *****)?

You shouldn't wish bad things to happen. Even if she's a b*tch, she's still your sister. You just need to talk things over with your sister. Tell her that she hurt your feelings. Trust me, the guy you're fighting over is not worth the relationship you're risking with your sister. There's a lot of guys out there. Hotter and way nicer than that guy....:)