Hey wishin
You poor thing. I'm sorry it's turned out like this.
But, better a thousand times that you split now, before you get any further through the pregnancy and especially before you give birth. Well done for taking this step - you've basically given yourself about a 1000x times better chance of actually enjoying and cherishing those early days and months with your lovely baby - instead of living in fear, sad and depressed, afraid of (by then) possibly even physical violence.
You're 20 weeks - you've got a while to go to sort everything out before the newborn days and before you get further into the pregnancy, which is great.
Keep him away. When he realises it's you making the decision to get rid he will change his tune - he'll beg, he'll promise the world, then he'll threaten. IT IS TEXTBOOK.
Don't believe the apologies - they are designed to win you around. Then it would be back to nasty nusiness as usual.
Don't believe the promises to change - as above.
Don't listen to the threats. Get someone to be with you if he threatens to turn up?
He is an abuser, as others have said. He won't change. And yes, while it's good for your baby to have a father in its life, no father, or a father at arm's length, is better than a violent abusive father.
You will be fine. Thank goodness you are financially secure. How is your support network - family, friends? Close? Good?