Hey man don't give up! Jeff Hanneman almost lost lost his arm. I did see the last time he played with Slayer (he only did South of Heaven and Angle of Death). In some ways you might need to relearn how to play. I have a group on here called "GUITARS ONLY!". If I can't help, I'm sure someone else can!

Try swimming, or a long early morning walk. Nature is very healing.

i used to play piano. circumstances changed.

play in your mind! listen to fahey, kottke, lang, blackshaw, or if you play electric, listen to young, clapton, hendrix, mayall, or if you like slide listen to lindley, cooder, raitt. close your eyes and play along with them until you know every note by heart and so do your fingers. i don't know how to defeat tendonitis, but assuming you'll eventually be able to play again, maybe this is the way to defeat stir-craziness while you wait.

g

I play flute. I love jazz, classical and some blues music.

Try physical therapy. And maybe a cortisone shot.

Sorry, wish I could help. I had a broken finger that stopped me from playing for a while earlier this year, so I understand. I don't know anything about tendonitis though.