I was suspended from school for sexual assault

There’s a girl in my school who I’ve known for a few years and I’ve always kinda had problems with. A few days ago she sexually harassed me by grabbing my private parts and saying “chode boy”, I was so creeped out and humiliated by it, but I told a teacher about it and they said they will be looking into it and talking to her. the next day I’m called into the office, as I walk in, there’s the head teacher, the girl and a bunch of her friends. The head teacher tells me to sit down and explains to me how He has multiple witnesses (her friends) that saw me sexually assault her and I won’t be coming back for a couple of weeks. The girls left and it was just me and the head teacher, I kept trying to explain that she’s lying and to check the school cameras, but he said “be happy she isn’t going to the police about this” completely ignoring anything I said

I genuinely can’t stop crying every time I think about it, why are they assuming something so serious with such little proof and they aren’t even listening to me at all. I feel so humiliated and powerless. I really really need someone to talk to. My parents have been trying to talk to the school about it but they aren’t talking to me at all anymore. I genuinely feel so powerless.