To feel hurt by this?

[Beetlegum]

Have NC as may be outing.
I have three fabulous stepchildren. All teens. I also have a 6 year old with their DF. DSC are with us every weekend. Their mum has a newish BF who none of them much like, and who her family can’t stand (due to some offensive behaviour towards them at an anniversary party, he is now banned from their family events).
We have limited contact with DSC mum now they are older, but usually she and DH text about holidays, big events, school, etc. Contact limited, but cordial.
Since I have known the children, every Christmas the arrangement has been they come to us Christmas Eve, then go back to their mum’s Christmas morning. One of the kids casually mentioned over the weekend that they were going away for Christmas this year with their mum so we would have to do an early or late Christmas. It came out of nowhere. DH is very upset, I felt hurt, our little one kept saying, ‘but you’ll be there for stockings’.
DSC are obviously very excited for their holiday, but AIBU to be hurt by this, and also a little angry at their mum? (Not hurt by or angry at DSC.) There was no conversation with DH before it was booked, even though they had a conversation about holiday dates very recently. DH plans to speak to his ex about this as it’s upset him and our little one and something he feels should have been discussed before booking.
DSC’s mum has a history of selfish behaviour, including abandoning her children to see a previous BF (she was lucky to avoid SS intervention as her mum covered for her when questioned about it), so this feels like small fry by comparison, but family time at Christmas, birthdays, etc is something we value highly and we feel she should have discussed with DH first.
Are we being unreasonable to be hurt by this? Should DH speak to her, or let it go?

I mentioned the BF in the post as they are all going away together (from what I understood from the children, mainly because he isn’t welcome at DSC’s grandparents where they usually spend Christmas Day)..

Hmm. She knows your DH will understandably be cross. You'll probably end up having all the kids for a week while she and bf swan off together.

Aww, I'm not surprised you're upset OP.

I would advise that your DH keep the emotion out of it and not tell his ex that he is hurt or upset, but to ask her from now on to tell him these things in advance as a courtesy. I worry that if it turned into a fight she would dig her heels in over it.

I too would be upset that this wasn’t discussed first. But maybe she thinks it’s unfair that you get to have the kids every single Christmas Eve?

It doesn't mean they have to go, just because she's booked it (especially as they weren't consulted). Make it clear to them that if they decide they don't want to go, they'll be welcome at yours for the whole week (or two, whatever it is). No pressure, but they have a choice.

They're excited about it so clearly do want to go. Where does it say anything about Mum wanting to swan off alone with her boyfriend? It's a bit sad for you but great for them and yes she should have mentioned it but I think this is a big overreaction tbh.

peterrabbitscarrots we’ve always had then Christmas Eve at her request. It could have been switched at any time. She has always wanted that arrangement so that she can go out for dinner with friends or bf on Christmas Eve and to spend the day with her family during the day.
DSC do want to go on the holiday, which is fair enough, it’s an exciting location (who wouldn’t want to be poolside on Christmas Day), we’re not upset by that. We’re upset by the lack of consideration shown by their mum. Though to be honest, we shouldn’t be surprised - she has done this before with birthdays, etc.
longwayoff that happens a lot too. She often doesn’t treat DH as their dad, just a convenient - and free - babysitter. She even uses the word babysitting when she wants them to come here outside of the usual arrangement.
DH wants to talk to her about to it to explain that they need to agree hols in advance, especially around important times. I don’t think she has even thought how it would be if DH sprung this kind of thing on her (which he wouldn’t). We have two big family holidays coming up over the next 12 months, and DH checked the dates with her BEFORE we booked them.