Save Sima’s life

We found Sima and her brother in a dumpster. Their newborns were thrown out by the owners after tying them in a bag so that they lost air. We heard their plea for help and rushed to save them. Unfortunately, her brother died a few days later. Sima's doctors later found a defect that made her unable to eat and too weak. Palatine cleft. There's a hole in her palate where food gets stuck and decomposes there. Because of it, she can drown and die. Now a year has passed and the condition is getting worse. The doctors say that we need to do an operation, but the amount that you have told us is too much for us. If you do not do the operation, then Sima will have tissue necrosis and she may die or remain disabled. I don't think animals deserve such terrible diseases. Please, please help me. We have no one to turn to, and I hope that together we will be able to save the life of the cat. She's too precious for me, and I can't live with the burden of not being able to save both kittens. hope for your understanding.