<human>: So my SO's brother and sil are here for a week over the holidays, and his mom has always been very insistent on everyone being at her house for Christmas day.  We oblige because it's not usually worth the fight - my parents just move christmas to whenever we are back home.  However, this year we arrived on Christmas eve to find that my mil is working today (christmas) from 7-3.  We did all of our gifts last night and woke up to nothing this morning.  Meanwhile, my family is spending christmas morning with my cousins and grandparents exchanging gifts with them.  We won't be seeing that side of my family at all over Christmas, and I'm really sad to be missing that, but we made the decision to miss it in favour of spending christmas with mil.

I am so upset with my mil but I don't know how to handle the situation.  I feel robbed of Christmas morning with my little cousins because of her manipulation.  My SO is upset as well as he would have liked to see my cousins too.  I want to say that next year we'll be spending the day with my family and fit mil in when we can, but I don't know if that's just going to cause more problems than its worth, and I think that may be more vindictive than I'm realizing right now.  My SO is 100% behind me, and even suggested leaving last night to drive the 5 hours home to my parents, but we decided it was too late.

So reddit, am I seeing this clearly?  Are we reasonable to refuse to come on the 25th next year?

Can you condense the text into three sentences or less?
<bot>: mil lied to so and I about Christmas plans, now we're missing celebrations with my family to spend the day sitting around the house doing nothing.  Not sure what to do or if we're more upset than we should be.