huckster...
Nyte is right. There is nothing you can do to stop him if he is going to use or if he already has started back down the slope.
He will do what he will do.
I know fear can be over powering sometimes. Maybe you can repeat the serenity prayer to yourself everytime that fear creeps up on you.
Take care of yourself, sweetie... take care of that back...and know that you have lots of prayers and support coming your way from your support system here at SR.
I'll say an extra prayer for you and your son tonight.
:praying