I don't wanna have my dog put down😭😭😭

Okay I have a rescue dog name blu ..! He's 2 or 3 and he's a game dog (Fighting dog/Murderer) the people we got him from was starving him & only used him to fight for money ..! He's scary when it comes to humans & love kids but other dogs 😐😐 Idk what 2 say but I just found my dog mouth full of blood & when I seen what it was I almost fainted 😰😱😲😵😵😵 It was my neighbors Chihuahua Pete 😣 my dog literally ate this dam dogs arm and you can see all of the insides heart & all its horrible 😭😭😭 now my neighbor is mad at me & told me I have to have him put down when I feel like it's her fault because she always let her dog out for hours & never look for him I always take him home because he's either about to get hit or kids are bothering him & My gate was locked & blocked off He did all he could to get into my backyard for his death & now it's all my fault Idk what to do ..! 😞😞 Any advice is welcome thanks 💕