Unfortunately coming to grips with the fact that there really is very little you can do, is going to be the hardest for you Al. It's an extremely addictive drug, and you just can't make any decisions for someone who doesn't want to listen. I'm very close to this issue, as my Sister is addicted to meth as well. Her 5 year old sons death a few years back is now highly suspect to neglect, and the worst part is there isn't a fucking thing I can do about it. Letting go is a bitter pill I'm learning to swallow, but it's so tragic.
Hopefully your friend will be one of the ones who reaches out for help, and has the strength needed to go the distance. I hope so for your sake alone Al.