If you cannot take the cat with you, please give him to a no-kill shelter. I volunteer at one and the people who are employed there will help him. They will isolate him for a few weeks, do medical tests, and give him some loving care and good grub. Please don’t euthanize him!
P.S.: It sounds like your cat was originally a feral cat. They usually bond with only one person. I have such a cat.
It’s been my experience that no-kill shelters are very selective about the animals they take since their space is so limited. Given his behavior problems make him virtually unadoptable, it’s unlikely they’d take him.