I have a soft spot for pitties but some dogs just have dog aggression, pit or not. Do you have a crate to keep her in? I am sorry it didn't work out, the shelter I volunteer at requires dog to dog introductions, although it doesn't sound like that would have helped since she showed no sign before, some dogs only get aggessive over food.

I hope she is not euthanized because of this, I sure hope they require her to go to a home with no other dogs. Is Nikki okay, I hope she isn't hurt.