Threatened by partner... trapped

I'm currently staying with my partner, but it's been a very long very bumpy road..

We were engaged, a LOT happened, we split up and got back together as we have an 8 month baby girl and I'm currently pregnant too.

So we came back so he could be with them really, and try work on things.

We've been arguing for the past few days, he's run up to me with my baby in my arms like he's going to hit me (we have a history of him being very very abusive before I had my baby), he then slams the pushes me out the room and slams the door in our face. This has now happened 3 times in the past couple of weeks. He did it again yesterday and I got so angry then I opened the door and slapped him (barely because he moved back), but still it was wrong of me, especially because I was holding my baby.

Fast forward to this morning and he was watching our daughter while I had my me time (supposed to be sleeping in because it's my turn). He was getting more and more aggravated with her, getting angry and shouting at me to come get her.. he always does this, he leaves her until she cries and I come in and take her. I tried to stand my ground this morning and make him actually be a father (he spends maybe an hour total with her a day).

Anyways, I eventually came and took her and me started to tell me how hes going to kill me and shoot me, how I keep pushing him and when he snaps I'm going to regret it. He told me the day that he almost broke my nose and strangled me (before I had my babies), he should have killed me then already..

I have no where to go.. I live in the UK alone with him, I have no family here.

I dont know what to do, I dont know how likely he is to actually do something as he hasnt been physically abusive since I've had my baby..

But I have my children to think of now.. if something has to happen I'd never forgive myself..

I dont know what to do....