AIO for leaving my fiance while pregnant because of his aggressive dog?

When we met, he already had his Amstaff which has lived in his backyard the entire time. My fiance never walks him, because he's very strong and difficult to take for walks and in the country side, most people don't do that (European small country). I've felt bad about the dog living in the backyard, but I understand why because the dog is really aggressive and has killed every cat, kitten and hedgehog that has come close to its territory.

We've been together for a year now, but 6 months ago I got pregnant and simultaneously, my workplace got shut down. I had to move in with my boyfriend during this because my pregnancy was starting to take a toll on my health at the same time. I even tried to work from home and I set up an office here, trying to make it work.

That has been completely fine, until the landlord (my fiance owns the house but not the land here) had to remove the garden area the dog has been in as they're going to start expanding for more houses to be built.

Now the very aggressive dog I've learnt to fear and hate is living downstairs, literally trying to get through the gates to get at me with his mouth frothing at me. I'm threatening to move out and staying out as my fiance refuses to do anything about the situation. What about when the baby comes? I feel like I'm in bizarro world that he is even denying my proposal to rehome the dog. But he's made his choice I feel. I don't see any other choice. And that dog is not thriving being that pent up and aggressive. Sorry for my English.