My ex and I separated around 2 years ago. We have one child together and are generally amicable.
He's never been brilliant with money although he earns a fairly decent wage. When we first separated I didn't ask him for any money to allow him to pay for somewhere to rent and get set up a home where our son could stay with him otherwise he wouldn't have been able to afford to move out.
Fast forward to now and we're both happy with new partners. He has our son 1 night in the week plus every other weekend (so 4 nights a fortnight). He also picks him up from school 4 days a week and spends an hour or so with him. This was originally to fit around my work (so I do morning drop offs as he works then) but I'm currently on maternity leave so it's just for them to spend time together at present. He more often than not gives him tea these nights. The arrangement has worked well and we've both been flexible when required.
Money wise he pays for half of his swimming lessons (so about £15 a month). I get all school uniform but if I ask him he will usually pay half (though this year he's so far said he can't afford to send it yet).
That's a lot of background but it paints a picture of our arrangement and how it works. So I have him the majority of the time but he is an involved dad.
The issue is, things are really tight at the minute. I'm in my overdraft every month. My ex also claims things are tight for him too, and yet I found out he's got back from his fourth holiday this year (second time abroad) when he went to an expensive area for a week in the summer holidays (due to his partner working in a school). They went away in abroad earlier in the year and he took our son to Cornwall for a week too (which I'm grateful for, he loved it). He also seems to make other reasonably flashy purchases (game consoles etc) which he downplays but they could be second hand etc. I don't pry into his spending at all.
My partner thinks my ex is playing on my soft side by claiming he's skint all the time. My partner has similar amount of access to his child with his ex and set up maintenance payments without complaint and without her asking because he said it's just the right thing to do. It bothers him that he pays out happily for his child but we're also struggling as we're financially supporting my child too (we live together hence finances being linked). It's not fair to say it's none of his business what the arrangement is between my ex and I because he is currently picking up the financial shortfall for my son which he genuinely doesn't mind. But on principle I'm not sure if it's fair?
I know I'm entitled to child maintenance based on the online calculator and my partner thinks I should ask my ex for payments, even if it's less than the calculator suggests. I feel like I'm being greedy rocking the boat when we have an amicable arrangement even though genuinely money is a worry keeping me up at night.
What's the right thing to do here?