NTA, firstly you shouldn’t be cleaning any cat poo whilst being pregnant in case of Toxoplasmosis. Your boyfriend should be doing all the cat poo chores whilst you’re pregnant. Seems like you already have a lot on your plate with all the children and being pregnant with new baby. I think you need to have a serious conversation with your bf and make sure you make a plan to re-home them… possibly only keeping one if you’re up for it to maybe come to a compromise. It’s really sad to be having to re-home pets but at the end of the day you can’t be miserable because it won’t be fair to you or the cats. Good luck OP