How can I prevent painful memories?

I've had a rough time at school for a few years. I have severe panic attacks and most of the time I faint and basically freak out. Sometimes I scream because it hurts and its a really scary experience. Everytime I feel like this is the last time and sometimes I get the feeling its literally ending. Its horrible! Anyway as a result of being at secondary school I found that many of the school kids began to pick on me. Calling me names like freak of lier (pretty standard). On one occasion I passed out in the snow and when I came to I'd found that people had spat at me and I had a cut when I'd been hit by snowballs and stones (we think). Since then things got worse and only recently have they got better but I still find that I'm scared of what might happen to me in public because of this occasion. What can I do? What do you think?