I completely understand. I find it embarrassing, at times, to say "I don't feel well" because it is to often that I don't. Teenagers do get older and one day they will see beyond their selves, ha---like in their 30's! I don't have the diagnosis, but have suspected that this isn't just arthritis. I can't make the pain disappear, but getting out or finding a focus seems to get me through. Other days, well...I find a blog like this!
Hang in there. I don't think you can lean on the kids for emotional support; they genuinely can't respond to your needs, but that's just my opinion and frame of reference.