Moral Quandary

Last week, I told the concertmistress of the one orchestra with whom I was sitting in that I may or may not come to rehearsals. I want to help the group out, but the music is stuff I played back in high school, i.e. painfully easy. The season finale of Lost is on tonight, too, and I don't want to have to watch it after the fact or search for places to download it. Also, my wrist has been bothering me again. I probably shouldn't even be typing. What to do??