Try to take a page from your husband. He's found an escape in deerhunting. I doubt he cares if he gets one and I'm willing to bet that a lot of that time sitting and waiting is spent in thought and pain, but it still gives him something that isn't family, isn't chaos, isn't grief. You truly need to find something to occupy you. Not something for your family, something for YOU and you alone.
If you like games, find others and organize a game group. If you like to work with your hands, take some classes and learn a new skill (crotcheting, knitting, sculpting, painting, whatever). Join a book club. Take a creative writing class. Volunteer. It doesn't matter what you do so long as it is something that you will enjoy.
It is okay to grieve the loss of the little boy who didn't become the man you thought he would. It is okay to be angry at your son for throwing the little boy out the window, for tossing your dreams for him away, for his stupidity. It is okay to have pity for the man he isn't but could have been. In many ways, you are going through the stages of grief:
Denial (it isn't his fault)
Anger (how dare he do this to me, his family, himself)
Bargaining (if I do X and Y for him, he'll quit using)
Depression (the sadness for his bad choices and mistakes)
Acceptance (he is a man now, he will make his own choices, I will love him regardless but I won't watch him destroy himself)
Unfortunately, you have to go through it more than once -- the first time to accept he had made his choices; the second time for the loss of who he could have been; the third time for his betrayal of your love, beliefs, values. I don't think it is in you to put it all into once category. I truly believe you have to do it in steps and that's okay, we all do what we can, how we can. That, too, is part of acceptance.
If you feel that seeing him will draw you back into enabling him, then don't see him. It is painful, but it is the right thing to do at this time. As you get stronger, you'll be able to see him. Just not yet.
(((STANDS)))