Help Luca make a full recovery ♡

My loving, wonderful, amazing cat is suffering. I was unable to care for her for a few months and left her in the hands of someone I thought I could trust. Turns out, they are neglectful people who only care about them. When I finally was able to get Luca back, she was brought back to me with more than an inch of her tail cut off, a large mass on her stomach, and extremely under weight. I immediately took her to the vet to find out that if antibiotics don't help her tail, we may have to amputate, and if the mass on her stomach is cancerous, there's a chance it's metastasized to her lungs. If that's the case, there's nothing they can do. But we do have a chance to catch it before it reaches that point, if it hasn't already. Like anything in life, the biopsy and having it sent out are both extremely expensive as is the cost of amputation if her tail doesn't heal. My baby doesn't deserve this. But she does deserve to get the best care she can. She's such a sweet, loving cat. The amount of damage this person who was supposed to care for her costs around $606, and that's not including anesthetics and pain medication costs. I want my girl to live a long, happy life. Please, help me save my baby.