I think more information would be good. What did she tell you before the punch? What kind of relationship have you had before this incident? What do you think she did it? Did she intend to hurt you? There were other people around - how did they react?
I understand that you are angry and cofused and your social phobia probably isn't making it any easier, but try to use your empathy and analyse your situation. Noone here can tell you what to do - you are the one who decides. Hope you'll sort this out.
(And please don't let it touch you too much. It's the teachers problem, not yours. Know your rights, don't let anyone abuse you, but think about her as a human. SHE has a problem. She can't do that and I'm sure it will have it's consequences on her.)
:wink: