I took a nasty fall in Cheer... now my stunt group is begging for forgiveness. What should I do?

I think that it is enough punishment for them to know that you got really hurt from that accident, and you shouldn't encourage them feeling bad by not forgiving them. I can understand if you were temporarily upset, but you have to understand it was truly an accident, no one meant to hurt you. You need to forgive them, and they know that they made a mistake so chances are it won't happen again because they will be more careful. If it happens again, then it may be time to talk to them or your coach about ways you all can be more safe during practice so people don't get injured like that anymore.