So. This might get a tad long. I'll put a TL;DR at the bottom.

I got married 3 years ago. I live in the same town as my parents with my wife and daughter with a son joining us soon. I met my wife at college and she moved here with me as we both had excellent job offers in town. 

My wife and my parents don't like each other. My father is a demanding man with what I believe to my Narcisisitic personality traits. My wife is a very independent aint-take-no-crap-from-nobody kind of person. Its not been fun, let me tell you. My mom just hates anything that causes issues with my father. 

So. Low to mid grade discontement on that front most of the time. Recently, we decided to take a three day trip to see two national parks before the new baby arrives. Somehow, pure stupidity I guess, me and my wife had a conversation about who should watch our daughter she had come away thinking we were asking her sister to come down, and I came away thinking we were asking my sister and mother (my Dad is out with work right now). So both parties get asked. A month goes by and the date approaches. The issue comes to our attention. 

My wife has asked my sister-in-law and she has taken time off work and planned travel to come and watch our daughter. My mom and sister are hugely, greatly, to my eyes unreasonably upset about this. My mother doesnt work and my sister is going to college nearby. I make the decision that its too late to call off the sister-in-law plan. So I tell this to my family and they explode. I mean. Three days of phone calls and yelling. My mother won't speak to me. Says I prefer my wifes family to my own. My Dad sent me a text today that says "Your daughters grandparents lose out to an aunt." As if there were some sort of relational hierarchy. I also told them that I think it would be easiest to let my daughter stay the night another weekend and just let my SIL take her this weekend. So not just "no" (they were very excited that this was the first time my daughter was to spend the night with them), I did offer a solution as well.

This is all compounded by my family feeling like we tend to favor her family, which I believe is because we kind of do because we don't fight with them. 

AITA? 

TL;DR

Accidentally double booked both my Sister in law and mother and sister to watch my daughter for a weekend. Family flips out like I've betrayed them because I decided since my SIL took time off work, she should get to watch my daughter for the weekend, and my family for another weekend. AITA? 