Oh I'm sorry you are having to go through this when you are already emotional! I can't find the thread now but I saw a similar one last week. A girl in the same situation as you, ended up her hubby went to his parents for a few days and then came back when he had time to calm down and realise what he was doing.
I think you need to give him some time to adjust. Is he one to talk about things? I expect he is worried and scared about finances etc. men aren't always very good at expressing their emotions. It doesn't make what he said acceptable though, like the others said you didn't make this baby on your own, so if you weren't using protection he must have realised there could be a chance. It's not fair to do this to you, and you shouldn't have to choose. If he does really leave over you keeping it then that's not your fault. However I think once he has some time to mull it over he will realise that he is being silly. I can't believe he would leave you and your children just because you fell pg? Maybe let him go and stay with his parents or someone for a few days and get his head straight? You don't want to be arguing as that will stress you out even more.
Sending you big hugs, I have a feeling he'll come round xx