Hello OC, it is so hard to stay by your boundaries. Just know that by making him be accountable for HIS LIFE, you are allowing him to choose how he wants to live. I am in a similar situation in that my son left his SLE due to relapse and now he is out of contact. I am struggling with guilt, but I keep reading the posts here that reinforce this:
1: You did not cause it
2: You cannot cure it
3: You cannot control it.
Your son will learn as all A's the outcome of the choices they are making. Give it up so that you can have peace. He has a car so he will not be on the streets.
My heart and prayers go to you for peace in your decision.
Teresa