Who is being unreasonable?

[TracyDraco]

I have received a text this evening from my XH informing me that our youngest has a school trip tomorrow (he’s in nursery dept therefore needs an adult to accompany him) can I drop the children off at his in the morning instead of dropping them off at breakfast club?
This is the first I’ve heard about said trip - his mum is taking him apparently. I’m annoyed that nothing was mentioned to me about said trip (we share custody - they are with until the weekend this week) I wasn’t even asked if I wanted to take him.
Anyway I suggested in that case it would make sense that they stay with him tonight -- I’ll be late for work if I have to drop them at his.
He’s refused as he’s “out” tonight- which usually means he’s staying at his GFs. Who’s being unreasonable me or him?

Ignore the posters who are suggesting you say 'how high' when your ex says 'jump' because otherwise the child misses out. This actually isn't about a kids trip it's about a 'Co parent' who thinks their own life takes priority over standing arrangements and that the op should and will run around in circles at v v short notice. Yes the school comms is an issue but a separate one. The OPs ex should have told, sorry, ASKED, her sooner, or (gasp) cancelled his date to have an extra night with his dc to facilitate the trip.