I had an extremely close group of friends when I was in my very early '20s. There were like 7 of us that hung out almost every day, smoking pot, drinking beers, going to shows, just generally having a blast. At one point my buddy got turned onto crytal meth and introduced it to the whole group.
It was fun at first, but I never really got out of control with it. I was working full time and going to school, so it was strictly a weekend thing, and I never stayed up for longer than 24 hours. It was like that with everybody for the most part in the beginning, but soon enough shit got out of control.
it's really scary and sad to watch your close friends drastically change and turn into different people in front of your eyes. The only thing that really occurred to me was to simply walk away from it and completely cut them all off. It was too much fort me. i said some really nasty shit.
I wish there could have been a different way, but I feel like the people I miss don't really exist anymore, so it might not have mattered anyway.