Sorry to hear about
your experience. I've had psA for about
3 years, but have had the diagnosis for a little over a year. My experience is that symptoms come and go. I once had to quit all meds because of liver problems, and was surprised to find that I got better for a couple of weeks. Then I started to get horrific pustular psoriasis, followed by a major arthritis problem. Then I started Humira and within 2 months am feeling almost completely normal.
One thing you should ask about if you have one (or a few) joints that are really swollen is a cortisone injection. I had a hugely inflamed big toe, and the cortisone injection worked immediately and lasted a long time. (It also hurt like hell to have it done).
My main point is that there is no reason to believe that you'll get worse and worse. The new medications are amazing, and there're going to be a lot more options in the future.
Good luck!