I've been going through more or less the same thing for more than 10 years now (24/7, etc). Thinking back, I think that around the fourth or fifth year was one of the most difficult times I've had dealing with the situation (not necessarily in terms of pain, but more in mental anguish). I had also hit the ceiling for available treatments--my neurologist at the Jefferson Headache Center said that they had exhausted their options.
The main reasons that I was so upset were pretty much what you've described. I felt defeated, I constantly compared my life to the way that it had been before the headaches started and I felt like I was letting down the people around me.
Now the main problem is this cognitive process, and I think most non-stop pain sufferers experience it. At that point, we've assumed since day one that there would eventually be some sort of miracle cure, or at least something that'd make things manageable. We've thought that we have to beat these headaches--and that not being able to do so is a fault--and, once we do, we can resume life right where we left off.
Unfortunately this is very rarely the case. I'd been told for years that I'd do better if I accepted my life as a persistent headache/migraine sufferer, rather than fighting against that reality with every ounce of strength that I had. And for those first 4 or 5 years I did constantly fight it. I thought "this is not my life" and "I'll only have my life back when I beat this."
At a certain point, however, we realize that we're not the same people that we were before and we very likely never will be. We realize and accept (mostly, at least) that our pain is unlikely to relent anytime soon. At this point there's a choice to be made: continue fighting the headaches with everything you've got and believe that your life will never be good again until you've rid yourself of your headaches or you can accept that being a headache sufferer is part of your identity. If you go with option number 1, unless you find that miracle cure, you're never going to be happy (and even if you did fully banish your pain, I think you'd find that your life would still be unlikely to revert to how it was before the headaches). If you choose option 2, you accept that, although your life is different, that does not mean that you can't be happy and functional.
When I reached the point when I had to make that decision, I was so exhausted and unhappy from spending years believing that I could never be happy with constant pain in my life, I was depressed to the point of considering suicide. Needless to say, I hope that that isn't a road you go down. BUt I realized that if I was to have any chance to be happy and be able to cope with my pain, then I had to accept that I am a headache sufferer, not just someone that's going through a temporary rough spat of health. Once I made that decision, I started to find things that could make me happy (or, at the very least happier) and make me more functional. The main lesson to take away from this (and I think almost every longtime pain sufferer will tell you this) is that you can have a good, happy life even if you're in constant pain. It may not be the life that you expected before the pain started or what you imagine things being life if you do find that miracle cure, but it can be happy, productive and fulfilling. This is one of the most difficult lessons to learn in living with chronic pain but it very well might be the most important.
One final note, I mentioned the importance of accepting that your pain is likely going to continue, you should know that I don't mean to imply that you should stop seeking treatment or lose hope that something might come along that does help a lot. It's just that you can't base your happiness on that possibility.
Oh, and one more extremely important thing. If you're struggling this much (which is a completely normal amount for your situation), you should absolutely seek out mental health care--at the very least a therapist to talk to and, if possible, a psychiatrist to help with meds. Living in constant pain, especially for as many years as you have take a huge toll on your psychological well being (I've often said that the experience of having had to live with more than 10 years of non-stop pain is a lot harder than the pain itself, a point I'm sure you can relate to).
I hope this helps. I know it's not easy. Also, if you want to talk about SSDisability (which I'm on, though it took me about 3 years to make that happen) or specific treatment options, I'd be happy to share my experience with you.
DX: NDPH (2003-present), Abdominal Migraine (2010-present), CRPS (1998-?)
RX: Lamictal, Indomethacin, Propranolol, Provigil, Viibyrd, Oxycontin, Clonazepam, Lorazepam, Melatonin, Magnesium
CPAP for mild sleep apnea
PRN: Oxycodone, Alprazolam
@ Jefferson Headache Center, Philadelphia, PA @