I think I’m going to say something a little different.
Firstly, I love cleaning. I now by choice have no cleaning help, but I did for many years when my children were small. I like things clean and very much dislike it when they’re not.
Your need for cleanliness may not match hers, and she may not like cleaning (now during pregnancy) or maybe never will. She may acutally dislike it VERY MUCH. In that sense it’s not going to work to motivate her to do herself (even for you who she cares about). A cleaning lady may also motivate her to keep things up in between the cleaning lady. I’ve seen that with people who generally dislike cleaning. The cleaning lady does the bulk, but it then motivated them to organize the closet, etc.
The fact that she gets upset at every disagreement and cries is manipulative in my opinion, although she may not be doing it on purpose. I think you should be able to talk about your feelings without her feeling you are demanding YOUR way. To be able to tell her you are uncomfortable with a stranger in the house, would prefer her to clean, but without her feeling threatened that you will NOT LET her have the cleaning lady. That you both can express your feeling about it. Give her time and space to do this in a unemotional way, where her feelings are understood. Then the two of you can weigh each one’s need and feeling and make a joint decision. If she feels heard and understood, she shouldn’t need to cry.
Sort of like kids arguing about who gets the first turn or crayons first, etc. If each feels secure they’ll get a turn, they won’t get upset, but will handle waiting their turn.
If she is getting very emotional about everything, this will not be possible and you may have to wait out this time period. This should pass after the pregnancy and post partum period, but if not you may need some help.
Also, those who are used to cleaning help don’t necessarily require nannies. If she does feel incapable of taking care of kids solely herself – that is her feeling. Your feeling will be discomfort with that. It may take her time to taking care of children. You may find you are more comfortable with a teenaged frum babysitter than a non Jewish nanny. But each person’s feeling can be discussed and take-in into account.
Much hatzlocha.