You recognise that this person won’t be dating you, even if you stay friends for a while, so unless you’re okay with just that and nothing more, don’t engage.

I think you’re hitting the nail on the head here. I say this a single mother: the moment my partner took on some childcare and I could start leaving the house for a few hours every now and again, my life changed. That mental break is so important. Find ways for your wife to spend some time away from the kids, just for herself, even once a week for an hour or two. It will help.

I think a much bigger issue here is kind of losing yourself in motherhood and not getting any time away from it all, forgetting yourself as a person with hobbies and interests outside of the parenting. How often does your wife see friends, goes shopping or to the SPA, or engages in sports or activities outside the home ?