I hope you will read around here Sasperilla. I think you will find that learning everything you can about addiction will be reassuring for you.
Always remember you didn't Cause it can't Control it and can't Cure it (the 3 Cs).
Trying to control an addict is not really to your benefit. Well, trying to control anyone at anytime is not to your benefit. It's perhaps a good idea to try to put more of the focus back on yourself and looking our for yourself.
Does he actually want to quit or are you "forcing" him to quit. I hope he is doing this for himself because long-term that's really a much more hopeful situation.