My MIL is nuking futs!

I recently gave birth to my daughter 10 weeks ago. We tried daycare and it didn't end up working out so my dad agreed to watch her while my husband and I work. My dad is retired now but he was essentially a stay at dad and raised four kids. He was awesome growing up and he cooked and cleaned while my mom worked during the day. (He owned his own business so his schedule was very flexible) he raised me, my sister and two brothers.

My parents are upper middle class and live in a large, ranch style home in a nice neighborhood and big yard. My dad cleans the house every day so there house is very tidy.

My dad loves watching our daughter as she is his first grandchild and she is a very easy, happy baby.

My MIL is furious that we did not ask her to watch our daughter. She not only lives in a run down trailer in a bad neighborhood, but she takes care of many foster kids as her source of income so there are several children in her care at any one time. She claims she is an expert child caregiver and she should have been the first person to ask.

I am trying to keep the peace but I seriously want to punt her head like a football. She keeps making passive aggressive comments like how it's weird that a grown man is watching his granddaughter and he is in poor health and should focus on other things.

I really wish I could just tell her that she isn't the worlds greatest baby sitter that she thinks she is.

The state is so hard up for foster parents that they will let just about anyone care for kids. Like literally her living room ceiling is black from mold (it's not toxic she claims!) every room is filled with crap like she is legitimately a hoarder. There's a small pathway in the house that you have to follow to get from room to room.

Her kitchen floor hasn't been mopped in the 17 years I have known her.

She doesn't do dishes so they just stay piled up in the sink.

The ac doesn't work so the house is always 80+ degrees.

I could go on and on about her nasty home.

My husband doesn't want to hurt her feelings but I don't even want my daughter there 1 day a week or even an hour. All visits are at our home.

But she keeps squawking about how unfair it is.

How can I tell her to shut the fuck up in a nice way?