Custody of Dog

[lovemydog]

In our divorce decree, custody of our dog went to my ex-husband as he refused to comply with the divorce unless he got him. My dog was to live with my ex and he was to be completely financially responsible for him. Let me state that I've been the primary caretaker and object of affection for my dog who was 2 at the time of the separation/divorce. A week after he took the dog out of the house, he called to say that the dog would not eat or sleep and was barking continuously. He stated that he would "allow" him to live "temporarily" with me ONLY if I agreed to pay for all his food and every other vet visit. I agreed as my children and I love that dog and having him out of the house was hurting both our dog and my family. My ex was supposed to find housing that allowed him to have the dog and then would take him. Instead, he rented an apartment walking distance from my house and stated that he "didn't want to pay the pet rent" and therefore would not be taking the dog now...but refused to give up legal ownership. Fast forward three years...during which I've been the primary caretaker for all his needs, paid for his food, every other vet visit, daycare, toys, etc. During that time, my ex saw him on average once a month for a couple hours at a time. He is now moving to a house that allows dogs...and intends to take the dog from me as he says he has "legal ownership." My dog has lived in my house since he was a puppy and is now 5 years old. I have been his primary caretaker the entire time. My ex did NOT live up to his "complete" financial responsibilities regarding my dog these last three years...nor has made much of an effort to see him either. My question is whether I have any legal standing to gain legal ownership of my dog and if so, how I would go about it. Thanks in advance for any advice.