Daze, I'm sorry.
I read extreme stress in every single line you wrote.
My general response is this: Do not, under any circumstances, quit your job and try to take care of your son. How in the world would you even begin?
I just read your signature and see that he graduated from college. He CAN DO IT. He HAS DONE IT.
You deserve a life, and he is a grown man, albeit with a lot of problems.
You can't solve them.
I know your pain is immense and I am sorry. I love the last sentence of your post. Do more and more and more of that.
Let the calls go to voice mail as much as you can. Say this: I love you honey, and I am sure you can figure it out. Over and over and over again.
I would type out a list of what I was going to say and carry it in my purse so I could whip it out if I decided to answer the phone. Otherwise, I was a jumbled mess.
You must focus on your own life as much as you can. Your son is getting services and he can choose to invest himself in getting all he can from those services...or not. It's completely up to him.
Please keep posting. We are here for you. Warm Hugs.