Do you have access to a veterinarian familiar with birds in your area?
If so I would suggest you bring her there soon.
If not, my suggestion would be to move her into an isolated area, preferably warm, with feed and water provided (away from flies)
I would then flush the wound copiously with an antiseptic like chlorhexidine.
https://www.tractorsupply.com/tsc/product/durvet-chlorhexidine-solution-2-59297
Afterwards, you can apply an antibacterial ointment such as Neosporin, or even medical-grade honey. The topical ointment should be applied several times a day as needed to maintain a moist wound environment.
The area is most probably infected, in which case antibiotics would be recommended; several can be obtained online in the U.S, such as Baytril.
https://allbirdproducts.com/products/baytril-10#:~:text=What is Baytril used for,Infections and many many more.
(Dose, 0.05ml per pound, twice a day, orally).
In addition with the wound care, try offering her warm electrolyte fluids to help correct any deficits correlated with the trauma of the attack. Weighing her on a gram scale from now on, each morning would help determine if there is active weight loss occurring, and if tube feeding would be required.