I'm going to break up my best friend's relationship.
Why would you break up your friend's relationship?
I want to be with her
It's terrible to try and pry into others' relationships. You should just leave them be.
She'll get over it.
She might get over it, but I still don't think it would be right for you to try to end her relationship. I don't think doing that will make her want to be with you, either. It would be best if you just focused on yourself, instead of her.