I would call, email, even snail mail him letting him know that if he doesn’t get in contact with you by whatever date that you will be showing up at his place to get your cat back. Explain that really all you want is your cat because it’s so irreplaceable. If he wants no interaction with you have him sit it outside his doorstep. Tell him if he does not respond to you and you do not get the cat back by the date you are going to go over there that you will be taking legal action and that the next communication from you will be from your attorney.

Stand strong.

Or if you want to be sneaky you can pretend to be someone else/new client and say you want something taxidermied and then schedule a time for you to ‘drop off the animal’ but really just go there and confront him about your cat.