Quicksand, I'm up early too.
Right now you are feeling the very natural feelings----pain and grief and fear and despair---of doing something new---setting new boundaries, with someone you love. Boundaries don't come without their cost---to us and to them. But they are necessary in every relationship we have, and I believe they are the hardest to set with our own children, because for so many years they relied on us for every single thing, very effectively blurring the lines between us and them. For me, I almost thought I WAS HIM, so the separation was very hard for me and for him. He was "my baby", right? Except now he is a grown man, and it's time for us to separate (way past time). I also had to separate and let go of my older son, who is not a Difficult Child. That has been hard too.
These things are necessary. But when a person is not functioning well, like your son and like my son was, the process of separating becomes so much harder. We are terrified for them.
But, as you know in your mind, you've tried it all and nothing has worked. Letting him go, figuratively and literally speaking, is truly giving him a chance to grow up and accept life on life's terms. Something we all much do as we mature.
But also, we have to watch in most cases, as they descend even further after we start letting go. Our FEELINGS say one thing---rescue, rescue, rescue---and our MIND says another---tried that, tried that, tried that.
We have to learn how to separate our feelings from our actions. And for most of us, that is a very very hard practice to learn.
Feel your feelings, but don't act on them. So...what do you do with the agony? Stay very busy, fill your mind with new thinking (this site, books like Boundaries, Codependent No More, Al-Anon literature), get a therapist, pray, meditate, exercise, do kind things for yourself. I call this assembling a toolbox, and then creating a daily practice of using the tools that work for me. Even just 30 minutes a day of something new, one thing different to take care of YOURSELF in this new way, will create a sea change.
I have walked this same path of sleeplessness (I called it the Parade of the Terribles, the nightly obsessive thinking about him), fear, unable to function fully, exhaustion, despair, grief.
I had to fully grieve the loss of all of my dreams for my son, as he was homeless, in jail over and over again, high, on and on and on. Unthinkable situations. I had to let him go.
We are here for you as you walk this lonely hard road. Believe me, we are not different here. We love our grown children very much and we have done the very best we could do all along the way. Now, we all have had to learn new ways of living and behaving, and we help each other navigate this new path with what we have learned, realizing we all go at our own pace, and many times one step forward and many steps back before we can go forward again.