You can also think about a different school placement - I don't know if he's in public school, but there are alternative schools that can sometimes help with behavior if started from a young age. The school I work in uses the Teaching Family Model and it is very successful provided the students are started in Elementary school - if they start in high school it seems like it's too late to shape their behavior :-/ many other schools use different behavior models but he might benefit from a skip up in structure. he would have to be classified for special ed though.

I would also try to find a support group in your area for yourself, it must be so hard dealing with all this! I know my son is only 2 1/2 and i thought his tantrums were super crazy and out of control but when I asked people I realized it was just normal. Not to say your son doesn't have issues just that it could help you feel less alone to find people who are trying to deal with the same issues.

I don't know if he's in therapy but talking to a behavioral therapist could benefit you as well because they can give you tools to use at home to help him out.