Hello and welcome to BYC! 
I am so sorry about your girl!
The first step is to get them through the shock, so keep her warm, 75-80 degrees for a couple days. (Shock will kill them faster than the injury) Around day 2, start her on antibiotics, Amoxicillin if you have it, and keep her on them for 7 to 10 days. She will be dazed for several days and will need coaxing to eat and drink. Do not let her outside around flies until the skin is sealed over, preventing fly strike and maggots. I hope she will be ok!

I am so sorry about your girl!
