I'm so sorry to hear about your girl!
The most important things are infection prevention and supportive care at this point.
Since this skin is open I'd avoid too must aspirin just to make sure she clots well.
I would clean it with an iodine/water solution if you have it, if not then saline wash or Veterycin work well too
Once its cleaned keep up an antiseptic 3x daily, blukote or veterycin both work well for this, I personally prefer veterycin but I'm sure theres some on here that prefer others. Whatever the case avoid alcohol and peroxide, both dry the wound too much and peroxide can do more damage to healthy cells than it does to damaged and infected ones.
Create a hospital if you can, a dog kennel works well for this with soft, dry, clean bedding. Keep her around 80 degrees F and make sure she has free access to water.
If she doesn't drink within 24 hours then start supplying the water either beak dripping or if needed tubing. I've found mine with a neck injury prefers the water right at the level of her upper crop so she doesn't have to extend her neck much.
Some electrolytes will help encourage drinking and give her some energy to heal with.
Hope this helps and hope your girl is doing better soon!
AJ