Welcome to SoberRecovery. I'm not sure of the laws where you live, but if your son is a minor you still may have some recourse in making him change his ways...don't count on it though, he's old enough (and it sounds like he has enough money) to just take off and continue his lifestyle.
Please pay attention to what Elana posted. YOU could be arrested, lose your home and have any other children taken away from you. It's not only the sad truth, but we had a member here not long ago who spent a year in prison, lost her home and her children just for "knowing" and for answering the phone, even though she didn't know that the person calling was a dealer. The police are not stupid, and if your son has been generating so much attention at school over his fighting and bad behaviour, and if he is a gang member (as it sounds like he is), then the police are already watching him and his comings and goings.
It's a dangerous life, that of an addict, and it affects the entire family.
Please stick around, read the posts and see what you are facing, and know that we are here to help you in any way we can.
Hugs
Ann