Breakup help, short version

My fiancé and I live together and I need to get out of this relationship. (I posted last night, so feel free to look on my profile if you want details). It’s not the best relationship. I was madly in love with him for the longest time and blind to how unhealthy it was, is the short way of putting it. I’ve known for a few months but it’s not easy leaving.

We got a dog together a year ago, he had one already, we got a puppy bc I wanted one. His dog was very much preferred to him (naturally) and I wanted a dog of my own. We both worked with her, but I’ve trained her in classes for the past year and worked with her daily. She’s about to test to be a therapy dog soon. We usually split bills equally, and consider things “ours”. We had the team mentality about bills at least.

But now he’s threatening if we break up he won’t let me have her. He’s about to be a cop, so I can’t call the police to supervise me moving out, and I don’t know if sneaking out while he’s at work is a good option legally. I don’t want to always be looking over my shoulder.

I’m working half from home and half in the office, and it’s affecting my work performance some days. Not only that but i just want to be able to breathe again and move on. Can anyone give any legal advice or have been in a similar situation?