Seymour, I'm sorry you are having a hard time. I think it's important not to look too far ahead. As Mary Beth said, all of life is uncertain, not just our disease. It's best just to live in the now as much as possible.
I also think it would be very helpful for you to see a counselor or therapist to learn techniques to control your anxiety and panic. Depression is an organic condition. It's not a sign of weakness. You talk about your battle with anxiety and depression and finding faith in treatments. A counselor or therapist can help you do that and could recommend medication if he/she thinks it would be helpful for you.
Hang in there.
Ginny - 58 year old female
Dx with USpA in March 2013; changed to AS in July 2015
Iritis and Scleritis, both currently in remission
unicompartmental knee replacements: right-June 2014, left-Aug 2018
MTX, Humira, Cyclobenzaprine, plus Celebrex as needed
Supplements: Folic Acid, Vitamin A, Vitamin D, Calcium, Fish Oil, Culturelle probiotic, Melatonin (as needed)