Welcome, Linda!
What a tough space to be in! We feel you!
So, do a little intellectual exercise with me. You don't need to respond on this board, if you don't feel like it (or even do it at all, if you don't want!)
What if you could trust that your 21 year old son could take care of himself? That it was healthy for him to take care of himself as an adult?
No one to pay his way or feed him? No one to call and wake him up for work? No one to do anything for him at all?
What would happen? What possibilities might open up for him?
A book that has helped me is Melody Beattie's Codependent No More. You might check it out. The stickies at the top of the forum are rich in wisdom, as well.
A second thing to consider is what kind of behavior is acceptable to you?
If you try to disentangle that he is your son and you love him and he is in trouble, ask yourself what is acceptable to you?
Is he doing drugs or drinking in your home? Is that okay with you?
Part of the journey we take (certainly I have taken since finding this board) is in taking the focus off my A and thinking about me and what I need and deserve in a relationship. I found some powerful answers in those questions and still and exploring it.
Welcome to a wonderful support.
You can make it through!
Hugs, peace