Yes, leave.
Seriously, pack a bag and go to friends or family for a couple of nights.
He can deal with children.
He can see how much HE relies on you for a change maybe.
He can wonder how he juggles childcare and work for a day or two.
And you can decide whether you want to proceed with both him and this pregnancy.
He sounds like an utter, utter dick.
And I can guess that no, you haven't gone from 0-100mph and 'Now I will never be able to escape you' just because he's doing some twattish teasing and laziness. Sounds like this is simply the tip of the iceberg.
If so, yes you can leave, yes you will be ok, yes you could do it with three, even though it would be tougher.
DON'T STAY because it will be hard for a few years - that isn't worth it if you despise this man as much as you sound as if you do.
If you want to keep the baby, you could make the decision in your head that you will be leaving when the newborn stage is over. That in itself could give you power and keep you going.