I'm so sorry you are going throught this. It's awful when we feel so helpless when it's our children.
Are you seeking any help for you with nar-anon or al-anon, counseling anything for just you?
Tuff love is how I am handling life with my son and his drinking issues. Your son has two feet and is capable of walking to where he needs to go or ride a bike.
Letting them suffer the consequences of their own actions instead of cushioning their fall really is help even if it doesn't feel like it.
Have you approached a doctor who specializes in addiction for a proper diagnosis? A doctor who understands the script approach isn't necessarly the right path?