In reply to tonanf:
Ouch! That sounds really scary.
As for the recovery, a friend of mine severed a tendon in his palm a few years ago and had to have his finger stitched to his palm and his hand in plaster for a couple of months followed by physio for quite a while. Hopefully your recovery will be much much quicker than that as the tendon that my friend damaged was one that closes the hand to grip not open it. Give yourself plenty of time to recover though, you don't want to damage it further by exercising it too soon. I know it's a pain but better to climb in the autumn than damage it further and not climb again until next spring. Keep training the other arm and hand in the meantime though.
Hope you have a speedy recovery.