Chicory, as a Mother it goes against our instinct to let go of a child. Not to stop loving that child but to save the child. Whether your sons problem is alcohol or mental illness. Both can be addressed in rehab. He has problems. You have problems. A solution has to be found to save both Mother and child. Since you are the stronger one, it's up to you .
Please go to your local Social Services and see what they have to offer. Whether it be an evaluation for mental illness or alcohol dependency. You need to try something different in order to change this situation. I would exhaust every possibility before living the way you are. I know your tired, I know your losing faith. Sometimes God gives you these burdens to make you wake up and help yourself.
There will never be a change until you make it. Gather your strength and do what you need to do . You'll be so relieved. There are millions of people who use Social Services to help them in time of need. Make an appointment. Go to the appointment. Listen, get answers and proceed from there. At least get their advice in person. Not a phone call.
I wish you the very best. :ghug3