I think a lot of people identify themselves by what they do, and that makes things much harder when they can't work because of a disability. Most people want to serve a purpose, and interact with others in the workplace.
I often feel stagnant, and left behind in life. It's a lousy feeling. I know that my disability is permanent. I know that it's hard to see the light at the end of the tunnel when you're in pain and suffering, but if there is a chance that your disability could be temporary, please try your best to focus on your potential recovery. Of course that does not mean that you're not entitled to your current feelings- they are justified.
Since your boss is still awaiting your return you must be one hell of a worker
It's nice to know that they will roll out the red carpet for you when you are ready to work again, and I hope that will be soon