Jay,
I understand being angry and not wanting someone to walk all over you. And if leaving felt like the right thing to do, then that’s great.
But you mentioned something about “his cat”. If you adopted two cats, he associated more with one and you believe he treats the cats kindly you should really give him his cat.
The less compassion we show to others the less we tend to show ourselves and that can be a problem since it’s hard to get away from ourselves.
Please do whatever you truly think I’d the right thing.