Hey OP. Big hug! I get it, you try and sort something and then in an instant a small person smears their greasy fingers on something, spills some juice on a cleaned rug or just empties their toy basket. It's exhausting, as well as then feeling bad for tidying and not spending time with the ones you're tidying for!
I'm currently 37 weeks pregnant and "nesting". I have moments of feeling insane when I look at a cobweb, dirty skirting board or mark on wall. Other times I tell myself that it's life and actually incredibly normal.
My advice would be similar to other PPs... dedicate small bursts to a quick tidy here and there, but remember that you won't be on your death bed wondering why on earth you didn't put more pairs of pants away. You'll be thinking of the time you spent with the people you love the most. They don't care what state the house is in, remember that (so long as they're clean, clothes are clean, there's a basic level of hygiene going on!).
It's also worth reminding yourself that your distress is likely due to comparing your household to others. If no other households existed, you would probably feel much better about the state of your house... and in this day and age its easier than ever to compare due to the content we can readily access of people's homes on social media. More often than not, such people have spruced up the room their filming in/have watched something back and thought shite, that looks a bit messy and then amended it. What I'm saying is, just try and live in your own little bubble whilst you're sorting things out, and bear in mind that when it's your home, you always see WAY more than visitors do.
Also, put some perspective on it if you're really struggling - we aren't living in a war zone, your children are fed, watered, clean, safe, loved and have a wonderful mum ❤️