We have had a bit of a rubbish Easter for one reason or another and I decided to look for a cheap trip away for May half-term to make up for it. My birthday also falls in that week, and ex and I have an unofficial agreement that I will always have the dc for my birthday.
I've been looking at flights, and considering a huge range of destinations (will just go wherever's cheapest!) but all of them are cheapest for the second half of the week, by quite a big difference - about £200-300, making it unaffordable as cheap 'extra' holiday/treat. My birthday is on the Thursday.
This morning the dc have come back from visiting ex and his parents and have announced that his mother, who has a milestone birthday that falls about a week before mine, is having a party the day after my birthday and they are invited - formal invitations will follow apparently. It is being held down the other end of the country, so will almost certainly mean them going down on my birthday, which is against our arrangement. I wouldn't mind that too much, as a one off, though it's annoying not to be asked but to hear it as a fact from the dc - but that's normal for ex. However, I really don't want to miss out on going away to accommodate this.
I also don't think it'll be great for the dc. There will be no one there their own ages. Ten years ago when she did a similar thing and ex and I were still together, I ended up holding the babies all day and being ignored by everyone. I feel it would be similar for them this year, but without me there. They are obviously older, so can be left to their own devices so will probably sit bored in a corner/ on dd1's phone or something. They would only know ex, mil and sil - and they would all be busy enjoying the party. Basically, I feel they would get more from being away with me.
WIBU to book my mini-break and feign ignorance of the party, as ex/mil can't be sure the dc have told me - don't think they were told to? Or I could say that I had already booked when the dc told me, but that means getting the dc to lie too, which I'm not happy with. The other option is being upfront and saying I'm booking anyway, and using my birthday as further justification, but that seems very confrontational and things are already bad between me and ex as he is contesting CM.
WIBU to do any of the above, or should I just let them go and miss out on going away?