The dog is the only way he can hurt you. Of course he will use the dog. What would happen if you let him have the dog? Sounds like he treats the dog well. If you were willing to walk away from the only thing that he could hurt you with, it may not be as much fun for him. While I understand that would be sad, it really is the only way for you to end this without a spiteful battle. Alternatively you could offer him a certain amount of money for the dog. Of course he wouldn’t take it, but then you would have set a value for him to match. Perhaps the law has progressed and I’m sure you’ve discussed it with your lawyer, but they used to be property. You could put the money toward a rescue dog and save a life by taking back your own. I hope you don’t think me callous, but the mental anguish you would save yourself would be huge and if the dog is well cared for I would consider it.