Tit for tat help

I need advice. How do you stop the tit for tat with your SO? I was never ever like this until we had children. He’s always that streak in him and it was tolerable, but it came out in full force once our first was born. ANYTHING that is done by him, needs to be done by me the next time. He’s constantly comparing how much we each do with the girls. It’s exhausting. I never used to think like this, but now my mind has shifted and it’s how I think. I hate it. It takes enjoyment out of everything. We are going to sit down and talk tonight because we had a bad argument earlier and told one another we’d cool off and talk later. I need to address this and come up with good solutions. I need him to realize the days don’t need to be 50/50. Some days need to be 75/25, etc. I’m sick this weekend so he has already claimed next weekend as “his” because of how much he’s done this weekend. Like what?