Cayce,
I agree with having a list of your boundaries, for YOU to remember. But for some reason, I fear your sharing it with him. If he got so angry at you once, he may again, and the list could just make him madder.
I feel very strongly about threats against people. especially women and children and unborn children. If you even feel like he is getting angry at you, I would call police, and have a restraining order against him, have a safe place for yourself to go to. all the above advice that Naive listed is great, as well as the other suggestions about calling DV authorities.
it just isn't worth the risk to hope he wont do it again. your little one at three will notice things that are not right, and he can be afraid, of things he does not understand. Of course you know this.
please follow a plan for your safety, and do not give your H the benifit of the doubt. if he is so depressed and drinking and threatening you at any time, that is so wrong, wrong, wrong,and deserves to be dealt with, with your safety in mind.
If he chooses to get well, it will be up to him to get his self inspired to do it. He will only get worse, most likely. do not let anyone do this to you- you dont deserve it!!!
hugs, chicory