Is it possible to help a dog that has been abused and fought other dogs for a living?

Hi i have 2 dogs a bichon and a pug/chihuahua that are 2 great dogs and today i just recieved another dog that is a long haired chihuahua that has been a dog fighter and abused. the ppl that gave her to me werent the ones who abused her. they only had her for a few days and are moving so they can no longer care for her so i said i could take her. she growls at me and my gf everytime we look at her and everytime we go to pick up her cage to move her. i am scared that if i let her around the other dogs then she will bite them and i would really have to give her away but i want to help her in anyway that i can but i dont know how to help her. she hasnt taken a bath but wont let me get too near to her. she wont eat or come out of her cage. please help me!! how do i help this poor dog?