Of course YANBU!
I wouldn’t leave my 10 year old alone all day in our own home, let alone a hotel, especially when ill! What completely shitty parenting.
We are ‘outdoorsy’ people who love a climb/walk/cycle and would love our children to enjoy this, too. I also totally believe that a little bit of endurance builds confidence and ambition, etc.
However, I am appalled at your DH’s attitude. How selfish (and sadly, I know quite a few men like this, where a holiday means indulging in their hobby and it being up to their wife to sort the kids out in whatever form. Never well enough, of course).
Holidays are a wonderful opportunity to spend time with each other, to unwind and to experience new things. For EVERYONE.
So we do a ‘big hike’ but edit it for the kids (lots more stops, little snacks) and then the next day we have a day by the pool or whatever. A long bike ride (which does call for some endurance on their behalf) and then the next day at a water park. One night in a fancy restaurant, one in an informal pizzeria with colouring in. Everybody is learning, everybody is catered for.
I think that’s called compromise and respecting everyone’s needs in the family. A.k.a not being a selfish bully 🤷🏼♀️
But all bets are off when a child is sick (how on earth does he need this explaining to him?!)
The next time your DH is ill, tired or stressed, berate him for having no ambition and sneer at him. Do nothing to help him.
FFS, what a wanker. I hope your DD feels better soon x