"And I was taught to never turn my back on someone who is doing the right thing." (inpieces314)
I do not believe allowing him to fend for himself is turning your back on him.
You are allowing him the dignity to act/decide/choose to be a real grown up man.
Sometimes nurture and guidance turns into smother and suffocate. And what happens when people feel confined/imprisoned? what does an addict do when they feel threatened? He will certainly rebel with the maturity of a 13 year old kid.
We have to allow others the dignity to thrive or fail.
Even though you are choosing to let him and his actions/choices effect your life, the bottom line is this is about him and not you. ( It sucks, but it's the painful truth).
Take sometime for yourself, make yourself the focus of your life. He has a long journey with his recovery, and if he really is going to work his program, you are going to have alot of free time on your hands, so why not invest some time in YOU?