he comes up with the baby and just dumps him on the bed
vs
I know..he wouldn't hurt him"
How do you think baby feels being dumped on the bed? He's a little person, not an object. What do you classify as "hurt"? Does he need to be bruised, bleeding, broken bones from being dumped the "wrong way"?
I'm so sorry you're in this situation OP. It's not fair, it's not what you wanted and it's not what you deserve.
The reason getting out of this is difficult is because you are not in flight or fight, you're in freeze. Your mind is no longer looking at what's going on around you and responding to it the way ours are. It's half shut down, numb. It's a totally legitimate response to threat. But you need to get moving.
You need to actively start to figure out where to go. First thing to do is speak to Woman's Aid.
You're going to hear your brain telling you it's not so bad, that it's easier to stay - anything to avoid it having to work. Remember this, because our brains always look for the way they think is easiest. When we're partially numb, its easier for the brain to stay that way meaning it's even harder to crank them into gear! But you absolutely can. Keep lists (somewhere safe) of what needs doing and work through them.
When you find yourself feeling that "it could be worse" or "I don't want to break up my child's family" or "it's just been a few times" then remind yourself that that this is not the reality. It's your brain being a lazy git! And you're going to ignore it and move on. (And btw you'd not be breaking up the family, he did that the first time he hurt you).