When I was in S3, my CHist teacher always insulted me in class, asked me to stay late at corridor after recess, lunch break, scolded me something I never did. My overall academic result was really good at that time.
After 2 months, I went to the teachers room during lunch, told her if I's late for any class cause her, I'll quit the school and reported to Edu Dept. She yelled at me in front of her colleagues. And everyone knew what's happened. I won but this is a really painful experience.
I sincerely hope you can treat this as a 'other learning experiences'. If you can't bare it any longer, you need to find at least one teacher you can trust, share your story with him/her, and seek for his/her advice. Share with schoolmates and your parents, if they support you wholehearted. That's what I did when I's in S3.