Dog custody through breakup

To start back in December we broke up due to her cocaine addiction. I had been supportive, even after she put my life in danger, even after she spent all our money. I stayed. Well she left December 19th and she originally took the dog. She had bought him years prior to us getting together but since being in the relationship for the past 3 years I have been the sole caretaker as she had bad priorities. In December when she took the dog she immediately tried to sell him on Facebook. I was able to convince her to bring him back to me. She is staying with family that doesnt allow dogs. I live on a big property with a fenced in yard and another dog he gets along well with (my roommates dog). So living here has been the best situation for him. I have bought his food, bathed him, bought flea medicine for him, loved him, cared for him and everything. Over the past 3 months shes worked on getting sober and was working towards moving back in. Still though I did most of the care for the dog. 2 days ago a physical fight broke out and I told her I was done and over it. Only thing she worried about taking was clothes and beer. She still hasnt asked about him, I did tell her she wasnt taking him again just to try and sell him again. She didnt argue it or even acknowledge it. I know she hasnt gotten him any shots in the 3 years we've been together. I have an appointment to get him his shots and a microchip. I guess what im getting to is, does she have the right to still come and take him? I have ordered locks for my part of the house and stuff incase she tries to come by while I am gone. I just dont know about the legal side of things…