there are 10 other players on a TEAM and if you lose a game then it is because each member of the team didn't do their part properly. It never rests on one person. Don't quit like scarecrow person said Quitting is just giving in and might make it worse, plus you shouldn't have to quit something you enjoy
have you talked to her and told her how it makes you feel? Or do you have some one you can talk to about how she treats you and how it makes you feel because it will make you feel better and if you can tell her how she makes you feel then maybe she might see sense
I have every class with my ex-bestfriend and over time I have learnt to just bloke her out, if she says hi i'm just polite and say hi back, it seems really difficult at first but it gets easier and its only 2 classes