Help pay optimus primes vet bill

On Monday November 13th my cat optimus prime was attacked in our back yard by a dog who belonged to one of my roommates guests. This dog is a sweet dog but is very aggressive towards other animals due to past events. The owner is aware of this and even let me and the other cat owner in the house know that she would attack our cats if she saw them so the keep them away from our roommates door. However for some reason on Monday she let her dog out in our back yard without a leash (knowing that there were other animals who lived there) and optimus was outside so the dog attacked him, luckily they were able to get the dog off of him before she killed him but after I rescued a very traumatized kitty from the shed roof and brought him insider to clean off all of the sort and twigs from hia underside his left hind leg began to bleed. I brought him to an emergency vet (after being assured by the owner and my roommate that all vet bills would be taken care of) and they took him in right away amd started the procedure to clean out his wound and put a drain in. I'm so grateful that they were able to help him and after a week of constantly watching him to ensure he doesnt hurt himself further and giving him 3 different meds 3 to 4 times a day he does seem to be healing well and we are down to one medication twice a day. In about a week I take him in to get the drain taken out. However I'm now responsible for a $630 very bill which I cannot afford right now. The owner has blocked me on Facebook and says she won't pay for bill. I have been reimbursed for $400 dollars I had to pay when I brought him in, so now we only have the other $230 to raise by next week to cover the remainder of the bill. Optimus is my baby, I got him almost 7 years ago when he was 2 months old. He means the world to me and anyone who has met him knows that he is just the most loving, chill, friendly and relaxed cat. He gets along with all of my friends and any animal he meets. He didn't deserve this and it could have been easily prevented by one simple thing, the owner putting a leash on her dog who is aggressive towards animals before taking her out in someone else's yard.... Where other animals live. So if anyone has an extra few bucks lying around please help me and optimus pay off his vet bills! We appreciate all of you.
-optimus & kelsea