I feel bad for the guy who got ostracized by you and your entire friend group because he occasionally did speed and admitted to it. I understand your situation but I also think at some point you need to be able to stand on your own two feet without taking such drastic measures. Strength is both being able to walk away and then to say no in the face of temptation.
I say this as someone who abused drugs when I was younger and came from an extremely abusive family environment.