I was going through the same feelings when I hurt my back a few years ago. I had a nerve pinched that took all the strength from my right quadricep. A chiropractor was able to get the nerve unpinched, but I needed physical therapy to regain the strength. After a couple weeks of PT, I was allowed to use the stationary bike. Then I went to riding a mountain bike on the road for a few miles at a time. After six months, I was back on the road bike. I'm glad I stuck it out, because, while I was recovering, I had tested a recumbent trike and it scared the hell out of me to be eye level with car bumpers.

Healing takes time, and when you are older it takes more time. Follow the advice of the doctors and physical therapists and you will get through it.