Look at this as an opportunity to learn an instrument that isn't as demanding on the left arm. Or a time to work on unaccompanied singing. Or throw yourself into some other creative pursuit (writing, drawing, computer stuff, etc.).

I developed a left-arm condition that kept me from playing fiddle for most of three years - I spent most of my music time playing harmonica. After a while, I was able for the most part to just not think about the fiddle. Of course, I already played the harmonica, but I was able to take it up to a new level entirely.

Good luck; keep moving forward.