There comes a time, a SAD time, when even Mom has to admit that a chronically non working, drug using adult is NOT just having a hard time growing up, but that our child is fully grown and just not going to do life as others do. We hate it but we know it and there is not one thing we can do about it except for embracing our own life, counting our blessings (God gives us all blessings) and letting go. 48, 49, 50. Your son is close to his senior year and still on a destructive path.
I have a disordered daughter in her 30s and there is nothing I can do to change her. Nothing. I pray. It is my only super power. I moved on, not easily! But it is what it is. We have no control over another human or our environment or what new instances come up. All we can control is our responses to whatever we face AND we can change our own path.
I read a great book called "Whatever Arises, Love That" by Matt Kahn (love him) and it changed how I see the world, especially challenges. I seem to be learning more and more about life and am on a forward path. I wish you could all share. There are paths to peace.
I am so sorry for your pain and wish I could wipe your tears. We are all holding your hands as mom's mom have been there. We understand. We are a loving team. We are always here for you.
Prayers...and look to the light in everything, even when in pain. You can do this. We will help. Love and hugs.