Household expenses are split 75/25
I pay for extra stuff on top of that like kids clothes and activities on my NWD with the kids
During second mat leave I ran up credit card debt to keep covering my share of expenses and have the time off, so I'm paying that off and not saving anything
I don't understand this.
Why was the credit card debt in your name only? Why didn't you both save in advance? Why did this remain just your problem to solve?
I know a few people have commented on how this would be treated differently as a post if the roles were reversed for sex and he was the higher earner but it's not the same.
Would he have covered your expenses to cover your 25% of the bills? Or would he still expected you to pay whilst you were on mat leave? This would be just frowned on by MN as Mum is doing 'labour for the household and investing in family' thus is contributing to the household.
Instead you had to do BOTH the birthing and maternity thing whilst maintaining all the financial burden.
This is where the 75/25 falls down for you.
You still take the financial penalty of BOTH the impact to your career AND the financial burden of having to cover the 75%. This is fundamentally different to a partnership where the man is the higher earner - he'd retain the stress of the bulk of the financial burden and tbh in a progressive arrangement you'd expect a recognition of your contribution to the household and expect him to take on extra financially responsibility during this period to bridge the gap.
Instead you have all the financial risk exposure and all contributed the physical labour. He didn't do either. At the very least, this is where shared financial liability should have kicked in, at least temporarily for this period of your life. Id argue that if you are 75/25 he should have been contributing at least 25% to that debt and had his name on the debt.
This makes a higher female earner relationship difference in its economic balance to one with a higher male earner and arguably they should be treated differently to take into account who takes the financial risk and the contribution to the household that the act of giving birth and taking maternity covers.
I suspect this is where resentment has crept in, despite him outwardly perhaps appearing more progressive than more traditional set ups. It's not actually as progressive as it might appear on the surface and it ISN'T a straight role reversal because of where burdens lie. Despite being a lower earner, he still should have stepped up in someway over that period and you feel like he hasn't recognised what you've done and how the burden has been squarely all on you. That's not expecting him to cover your 75% of bills - it's expecting him to contribute to some of the shortfall over time - stepping up to help even if it's a small percentage rather than you shoulder it all.
It's not so easy to see this inequality - it's the hidden labour issue. Having a child is a financial contribution to society and a provision of household labour even though it costs money. The fact he does some household stuff and is the lower earner disguises this.