Clearly your BF is an addict. You did not make a mistake by breaking up with him.
It would be a major mistake for you to continue trying to be in a relationship with him.
As the others have said above, just completely let go of this self destructive addict & do whatever you need to do to get past it. Let him go drugging, partying, & gambling with his friends.
Focus on 22 year old you & all the good things which life has to offer.