There no need for sorry dude,I've learnt upon that you had wrote
apology letter to her but had you ever talk to to your groups of
friends how you feel when they treat you that way and that you very
sorry about wad you had done. If i'm not wrong, that just won't
forgive you and just treat you as a 'criminal'.
I strongly believe that everyone deserved a second chance to
change, just like the yellow ribbon campaign. Friends like that
ain't worth you dreading on, life still have to go on, as you grow
older, i am sure your circles of friends would have expand.
I understand your feeling of being treated this way but maybe you
can talk to a teacher which you trust,but if you really feel very
stress, transfering school may help but you must praticed
self-control, as even if you transfer to another school, if you
continue to have anger-management problem you may faced with the
same problem again.
Every single person have different talent, continue to
self-improved and reflect on your own and soon you won't feel so
left out. All the Best!
*Cheers*