Vet bills for shot kitty

This is Darby and he's my family's kitty. We adopted him as a stray to try and give him a better life. We let him out yesterday morning for only a few hours (we monitor him and bring him in by afternoon) and he came back to us horribly hurt. We brought him to the emergency vet hospital by grossmont center and found out he had been shot with a pellet or air rifle gun. He is most likely going to lose his eye and if they can keep it, he will be blind in that eye. He also has extreme swelling and bruising to that side of his face and jaw. Our vet bills just yesterday came to $2500. We are taking him to a specialist today to see if his eye can be saved which is also extremely expensive. My parents are on a fixed income and I am not working right now. Anything you can do to help would be greatly appreciated. I know I have a lot of animal lover friends. Some evil person purposely did this to an innocent, sweet animal. I hate asking for help but if anyone could help out, my family and I would be eternally grateful. Thank you.