Sorry about your cel Anna, that sucks.

It happens though, and nothing can be done. When 
I first started a while back, I got caught up in 
the whole "layers should be separated" ideology 
everyone was spouting. So I carefully tried to 
separate two layers on one of my favorite cels 
and tore a huge chunk of paint off the top 
layer. Why I didn't practice on a lesser cel, I 
don't know. Moral of the story...stuck layer 
stay friggan stuck.