Historically difficult MIL - lots of falling out within family. We have avoided it as we have 2 DC she wants to see and I have been very direct and honest with her when she is out of order.
She has spent every Xmas with us with the exception of two. This has meant for the whole season - 2 weeks covering Xmas and New Year as she lived abroad. Sometimes with her husband, sometimes without, when they had difficulties. The run up to them not spending Xmas with us for 2 years was when her husband (in the October half term visit) was drinking gin at 11 o'clock in the morning, drinking and driving and acting very worryingly and strangely -all while my DH was at work! I spoke to MIL about this before the next Xmas saying I could not have that type of behavior in front of the children, although we would like her to spend Xmas with us, and she (thankfully) said it was better not to come.
Since this her husband has died and she is now living in this country and has spent Xmas with us, for the whole 2 weeks as she is on her own and sees no other family.
This year she announces she is going on a 5 day holiday to France with a new lady friend 'as they would both be on their own'. I was amazed and said so you won't be staying with us then? She sort of waffled on about not knowing what to do if I asked her (I always do and if not talk to her about why, for 13 years!). AIBU to be upset? I know its petty but I would never have organised Xmas without considering her. I then get a text a week later saying she is not going to France and hopes 'I haven't left it too late to spend the time with you all'. AIBU to be really pissed off? I am!