I haven't read many of your comments here and I think its complicated.
But I think that this child should have been taught that this is not a way that society finds acceptable to deal with a problem.
I hope that both girls get support and help to move them forward in life.
Shanni will carry the scars for the rest of her life, payback for her bullying will be visible for everyone to see. That's a life sentence. Poor child would probalby grow out of her bullying and it probably comes from a deeper problem anyway.