Did you look at https://www.painscience.com/? That site had info that cured nasty chronic pain of mine that lasted >1 year. This tutorial in particular was extremely helpful: https://www.painscience.com/tutorials/trigger-points.php
To answer your original question: when I was dealing with chronic pain, I had issues with deep despair similar to what you describe. My chronic pain left me unemployed, and I was constantly in fear of doing things that would aggravate my condition and set back the (very slow and variable) progress it was making in resolving itself. Definitely an extremely miserable period.
Thoughts I had that I found helpful and I'll pass on to you: I decided there were basically 2 strategies for dealing with the pain I had: cure and mitigation. Cure refers to finding a way to roll back the root cause of the problem and return to being my pain-free self. Mitigation refers to accepting the pain and finding ways to work around it (for me--finding a job that doesn't require me to make use of my hands at all, and probably doing a lot more meditation). I decided that it was best to focus on 1 strategy at a time, and that I should focus on the "cure" strategy for at least several years before switching to "mitigation". (What's a few years when I had decades left to live?) I realized that any given "cure" had a pretty low probability of working out, and being in a state of deep despair was extremely non-conducive to trying things that individually had a small probability of working out. This observation was helpful for recalibrating my intuition, and I resolved to make the "list of things I had tried" as long as I could possibly make it. I also resolved to do more of a breadth-first search than a depth-first search, at least at first--I didn't want something that would gradually fix my pain over the course of many months in a way that I would need careful journaling to observe--I wanted a technique that would help things noticeably, that I could use at any time, if the issues came up in the future. Luckily I did manage to find such a technique, which was trigger point therapy (see above links). I've since helped a few others make progress on their pain using trigger point therapy, and I think it's potentially useful for many, perhaps almost all, people who suffer chronic pain.
Some more specific recommendations:
If you're not already taking something, start taking SAMe. It's a supplement that you can buy over the counter that's anti-depressant and has been shown to be quite useful for arthritis (so who knows, maybe it will end up helping your condition somehow--it probably hasn't been studied for your condition and you may as well do an n=1 trial). Ideally it will improve your mood, which will give you the motivation to try low-probability treatments, and it might fix your issue on its own. Here's more info: http://www.lifeextension.com/Magazine/2007/4/report_same/Page-01
Read this book: http://smile.amazon.com/How-Fail-Almost-Everything-Still/dp/1591847745/ Not only is it an great book in and of itself, the author covers mental strategies that are ideal for chronic medical condition sufferers. And he uses the story of his chronic medical condition as a motivating example through the book, so it gives you something to relate to.
I've seen you mention trigger point therapy before. It's something I do, and it helps to a degree, but it has not had made a large change in my quality of life.
The rest seems worthwhile. Thank you for that.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.