Dear Dancing,
I do understand that dark, lonely place...without hope of ever feeling better. I too want to lie down and be done with it. Battling physical AND mental illness is a beast. The only thing I can say is to consider the others in your life (even if you are not close with them at this point in time) We DO matter to others, even if you have to look hard to discover who those people might be.
I consider myself in Critical Condition at this point in life, experiencing physical and mental suffering daily. Finding reasons to continue can be very challenging. I DO believe there are answers out there that will make life more tolerable. My job is to hang in there long enough to find something/anything that may help. I too am exhausted and understand your desire for some relief, some peace. It could be right around the corner... Just "be" for today, no need to make any decisions right now.
And... As always... Consider a trip to the hospital- we DO care about YOU!