I'll start out by saying DH and I have been together for 12 years and I had a wonderful relationship with MIL before kids got thrown into the mix.
SIL had her little boy 3.5 years ago and he was the centre of the universe, understandably. We then had DD 1 year later and honestly, she paled in comparison in MIL eyes - there has been obvious favouritism the entire time, and it's been pretty exhausting, ending in quite a big argument last September on a big family holiday, which marked the end of group holidays. But bridges have been rebuilt and we basically stopped doing things as a large group, and encouraged 1:1 time with MIL and DD instead, which was going well, DD adores her.
We decided this year to book a 3 day getaway, me, DH and DD and invite MIL and FIL and pay for them as a thank you for all the holidays they've taken us on over the years. it's a centre parcs break. We are travelling up, staying one full day and then travelling back. It's about a 1.5 hour drive. This has been in the diary since summer, and we all knew the dates.
MIL has text me today to say she has 'unintentionally' double booked and it's DGS nativity play on the only full day we are there, so they are going to drive back for it in the morning, and then come back in the evening - essentially they will be gone for 6 hours. We'd booked a santa visit, lunch etc that and I'm bloody hurt that she couldn't just say no this time.
I know it doesn't matter. DD is going to have the best time, we are going to have lovely family time, but ffs just when you think she can't let you down again.
AIBU to feel upset about this? I haven't replied yet. I want to just say forget it, don't come if you're going to miss half the trip and activities, but DH thinks we should just let them do as they please and not let it spoil our time.