But how could she have the audacity to publicily shame me for being humiliated in front of the whole school like that? We stopped talking for several weeks but then made up. The problem is everytime i look at her I see the same person that back stabbed me emotionally. I just want to know if I am being petty by holding a grudge against her or do I have every right to feel the way I do about her and should I just leave her?
From what you are writing I am guessing you are a teen. I have a teen daughter (and another now in college) and I have seen/heard the drama.
How could she shame you? Probably trying to make herself look better/more popular/cool or some other disingenuous reason. It seems this trying to be more cool is more important than being a true friend.
It was very good of you to forgive her, but you might want to think about being a close friend of hers. I would not trust her - she may turn on you again just look better in front of others. Did she give you a reason to make you think she might really be sorry? Either in action or sincere words?
I understand that being a teen can be hard and sometimes even nice people do cruel things - but if she did not seem sincere or show you some way that she really is sorry then you may be right to feel a grudge. I wouldn't necessarily call it a grudge so much if you feel she is not sincere as in protecting yourself. It could be that your instinct is trying to protect from further harm.
I suggest if you think there could be some sincerity you give her a chance (forgive - but don't forget) and if she shows this cruel side of herself again you drop her. If you feel she is being insincere then you might want to drop her now. You should surround yourself with true friends, those that pick you up, support you and will be there for you. It is tough enough to be a teen without having a toxic friend.
I've seen it with my daughter and I know how hurtful it can be.