I'm sorry for both of you. I really am, and you are in a situation no one tells us how to deal with.

And now I'm going to be harsh: You have to stop being afraid to feel bad yourself. That is the first thing you absolutely have to do. You enable him because you are so afraid of feeling bad and guilty you rather give up and let him eat himself to death. If there is Anonymous Codependents in your area, go into their meetings, no matter how much you keep telling yourself your son is the only problem here he is not. You are a problem too. You have to deal with yourself first before you can help anyone.

Everything I have to say about this you can learn in CODA or in therapy with a therapist who understands codependents so I won't dwell deeper into this. Just, if you want to help your son, you have to deal with yourself first.