mother in law

Am
My mother in law wants to fly up here and stay for a few weeks in our home following our daughter being born ("we will be here this time period after so I don't have to share her with your mom or any of your family. So this can be MY special time with her" -MIL). My husbands mother and I don't get along very well. My husband and his mother don't get along very well, there is always a lot of yelling and passive agression on her end when they're in the same room together. I have tried telling her no she doesn't need to stay to "help out" (she doesn't even help out in her own home. She doesn't cook, clean, work, or network.. she just... she just sits in her recliner all day for the last almost 30 years {no health issues or reasoning for it, she just didn't want to work anymore}) that I'd rather she just stay as long as her husband does and as long as my husband is on leave for. She won't take no for an answer and my husband won't tell her no because she guilts him and then goes to her other other kids and tells them how awful he is if he doesn't go with something she wants. 
Is there ANY advice on how to handle this either to make her not stay longer than her husband plans on staying or even mentally preparing myself for all the yelling and bitching that I will be dealing with post partum while adjusting to having a newborn? 
Her husband is great and my husband is great but no one seems to stand up to her because she "gets depressed easily and is bipolar". 
HELP!!! 😭😭