Thanks for all of the support guys!

I suppose i could make a new fin but there is no more extra balsa in the kit so id have to go and buy more sticks to make another fin.

Ill try to first fill it in with balsa and glue and if that doesn't work then ill cut away the screwed-up portion of the fin and just rebuild that part instead of starting from scratch (so to speak)

I just have one more question... what is considered "balsa filler"?
Is it just slivers of balsa that are CA'ed into cracks or is it something else entirely?

Thanks for all the great advice youve already given me!