Just no.
Sitting in a car, crying baby, have to stop to bf, struggling to latch, waiting whilst baby feeds for ages, needs nappy change, all in car and most likely tipping with rain, then drive arguing quietly and or crying, baby starts screaming as hates car and wants a cuddle, stop to bf etc etc
Arrive at mil, she snatches baby who starts yelling, bf in room alone, as milk going everywhere as baby won't latch. Mil bursts in getting a look at your boobs and giant tummy, dh finally appears with tea and cake, baby needs changing, you need the loo, Ffs baby wants to feed again, your dress is now ruined by milk, you begin to hate your dh.
Then you stay in a house, listening to the party, can't have a wee in peace, have nowhere to put giant sanitary towels, baby yells all night, mil says hers didnt, you take offence and vow never to see her again.
Then you get in the car and drive home, sobbing quietly and having to stop every 20 mins and baby wants to feed, hates car, wants to be cuddled.
Just say no. And have Christmas at home.