OP
I'm the mum in this situation.
I earn far more than my ex husband does. With 2 children.
When they were younger, yes I expected him to pay half h the child care so that we could BOTH work. Because it's very difficult for most people to get more than 2 weeks off over the summer holidays,
With all due respect, you sound very naive, do you still live at home? Just curious.
I'll tell you now, despite the fact my ex husband has the children 3 nights a week, sometimes 4, my outgoings are considerable higher,
Because although we've got no childcare costs theses days, they grow like weeds, they eat like bottomless pits, I've just bought my son his 7th pair of school shoes this year alone, I'm guessing your do doesn't chip in for uniform costs either, which is a year round thing not just a one off cost,
School trips
Money for them to go out with friends
New clothes
Snacks
Sports clubs
Swimming lessons
Energy bills
Other bills.
So you have no idea what her disposable income in, unless you've seen a full breakdown of her bank statements.
Why begrudge her a meal out with a friend? She works full time and has young children.
It really isn't your business. He's not asking you to pay,
It only becomes your business when you do plan on living together. And at which point he shouldn't change anything with HIS children.
I also imagine is she's earning 40k her UC amount will be very little.
You have no business dictating where they should send their children for swimming lessons,
Why should their life change because their parents have split up, they both still have responsibility for the children