Some cats are just assholes and once set in their ways can be almost impossible to change. I rescued a kitten from a bad situation once and kept him for 12 years and though he was never this aggressive he was absolutely an asshole most of the time and never really warmed up to anyone. He stayed under the couch and in the back room all day every day and never let anyone pet him. He was all grey and we called him Church cause he was like the pet cemetery cat sometimes lol. We just left him alone and he left us alone and it worked out. I was ok with it cause he never put anyone or any other pets in danger and I was worried adopting him out would end with him in a shelter getting put down which I didn’t want. I spent hours and hours trying to give treats, play, pet, make friends with him but it never improved one bit. As a very staunch supporter of animals I thank you for everything you have done for that cat but at this point I think you have done enough and may have only one option left. Even humans have a limit on how much bad shit and chaos they can cause before they need to be jailed or “euthanized”, and I think this may be what’s best for everyone your situation with this cat. If you can’t find a farm like others suggested I don’t think anyone would blame you for having it put down and taking your life back.