Very touching post. I like that question 'what is this misery'. Probably, everyone has a different answer. For me the best explanation came from Mate Gabor. He is MD, author of several books, known for his unusual heroine addicts treatment. To me he explained so well why some people become drug, alcohol, food, shopping addicts (himself) while others not. It was interesting to learn that out of all Vietnam soldiers who were taking drugs during the war, only 10-20% of them, became addicts once war had finished. He is arguing if drugs were addictive per-se, all of them would be addicted. You can find his videos on Youtube and I highly recommend. It really helped me to understand core of my addiction.
I can very much relate to your post. I lost 90-100lb, mostly through fasting and for me that was the easiest 'diet' around. Never lost a pound on any other diet. Every diet finished in binging. However, in my experience fasting was very seclusive and lonely activity, contra-intuitive for sure. It reminded me very much of that story (The Void) about a climber who felt into a huge crevasse, which he couldn't climb back so instead he declined himself further into darkness, hoping he might find an exit (or death). This is how I felt, that I have to go further into darkness and loneliness in order to find an exit from hell. Part of me welcomed solitude, but part of me screamed against it. And while hunger was not such a challenge during those fasts, overbearing need to 'live my life' was.
I found that climber story so inspirational that there were days during the fast when I watched it 5 times in a row. I felt as if I'm hanging on that rope as well. I felt the same desperation and isolation and I felt if I don't help myself no one else will. No one else can. Because the bottom line was: I had to do it, no one else could do that for me. You have to go in that crevasse on your own. And it is dark and lonely there, for all of us, it doesn't matter how much 'support' we do or don't have. But of course, since you've decided to go on that journey it helps to get equipped, the best you can.
Also, since I was 100lb overweight and couldn't fast all that weight, I found another thing very useful and that was juicing. Mostly veggie juicing. It prevented me to go back to bad habits, it gave me that feeling of being light and healthy, regardless how much juice I drank and I drank as much as I felt like. And at the same time, I felt I was able living my life as I wanted, without any restrictions or isolation. You sound as a very active person and if you find loneliness unbearable maybe that would be way to go.