You need to find a therapist to help your son. He needs to have someone he can talk things out with. He probably feels lost right now and is angry "with himself" but lashes out at others. He needs guidance. 21 is a challenging age, at this age guys feel like they are supposed to know who they are, what they want and have a direction. Well, most don't really have a direction at this age. He needs to be able to talk all this through.

Keep Posting, maybe even tell him about this site, there are a lot of members his age that struggle here.

Welcome to PC.
((Hugs))
OE