Honestly, I would be very surprised to hear of any married couple with children that small who are blissfully happy all the time. It must be completely overwhelming sometimes (most of the time!) with those ages, and my own natural instinct would be to blame my DH for absolutely EVERYTHING, up to an including him breathing at night. And he would naturally push back against that pretty vigorously, so we would end up hating each other for a good bit of the time. I think that's only natural (nature's way of stopping you adding a fourth baby to the mix!?).
I think that from what you describe, counselling should be your first step, not working out post-split finances. How have you been feeling in yourself since the baby was born, besides utterly exhausted?
I think it would be more weird if you always thought your husband was fantastic, under your current circumstances. However, you presumably married and had three children with him for a reason, so he must have some redeeming qualities, and you WILL start having fun again when Baby 3 is sleeping through the night and you start getting out together more.
Fighting because you are both overtired and freaked out about having hundreds of small children isn't the same as emotional abuse. Apologies if you are suffering real emotional abuse, but what you say suggests more that you are going through a stage of hating each other a bit, which is very different, and is fixable.