As a parent I would NEVER EVER tell my child they had to get rid of their beloved pet, thats very cruel indeed. Obviously he is not a real animal lover, or he would know how much hurt this is causing you.

Take the others advice and lie low, hopefully he will change his mind, or try having a heart to heart talk with him, find out his reasons, come up with some suggestions, and tell him how much it would hurt you. GOOD LUCK sweetie.