17 months is a fantastic achievement, congratulations!!!!
Addiction is soooo hard for both the addict and those who love the addict. This is his path to walk, his recovery to reach for, or not. I, too, will keep your friend in my prayers.
There are many on this site who are "double winners" who utilize counseling or a group program for their addiction as well as Al-Anon/Nar-Anon. Perhaps check out a local "Anon" meeting and see what you think.
Hugs, HG