You must do what you must do. It's just that simple.
Now, with that said, don't be suprised if your enabling just extends his fall to his bottom.
To me you are going thru the guilt/what if game. Guilt is a self imposed emotion, we humans have imposed this on ourselves to reason out our behavior, to make bad decisions livable/acceptable to us. What if I do this. Oh, I will feel so guilty.
In the meantime, in your case, your son is pulling every trick out of his hat, so, that you will do what he wants, and of coarse if you don't, that old guilt miester steps in, so, you cave.
I will just repeat what I have posted before: "It's now or never"...this will not get any better until you do whats best for him...stand up, stand firm, let him grow up and face his addiction straight in the face.
Just my two cents. The bottom line is that it is your decision, no one can make it for you.
I wish you enlightenment and peace.