Going back to school for exams- how should I behave?

I left high school late last month and I have to go back to do my exams there. The only thing is, when I left most of my year were a bit resentful towards me (a boy attacked me in PE and hit me in the back with a metal pole, because I needed hospital treatment we got the police involved and he got expelled because of it). Many people just think I'm stuck up and a bit of a b*tch because I got put up a year and so I left high school a year earlier than I should've. I'm scared that they might start taunting me or something while I'm waiting to go into my exam, and I really really need good marks in these and having people making remarks to me won't help at all because I am so nervous. Help?