OP, you're not a martyr. No one here knows what your life is truly like.
Your other half sounds very similar to mine. I strongly suspect he is neurodivergent (in fact, I know he is, but he is undiagnosed and refuses to be evaluated) and that brings issues that have only become exacerbated since having children. He doesn't really know how to look after babies or toddlers, and needs lots of mental rest. Having a child has changed him fundamentally, not in a good way, but I still love and need him in many other ways. I would never leave him, even though I'm struggling too and long for a break myself. We also have no familial help, sadly. I am just trying to make it through the early years and hope we will still love each other at the end, but sometimes it feels impossible to see the woods for the trees.
It goes without saying that this isn't the case for all men, but a lot of men - in fact I'd venture to say most men that I know in relationships and with children are just like this. Men don't think the same way as women do. Our children are the centre of our world. 98% of my daily thoughts are about them and my priorities for them, I just don't think it is the same for men. It's part of maternal instinct, in my opinion. I can cope with so much more than he can before burnout sets in. Doesn't make him a shit person, it's just who he is, as you said upthread about your partner.
Would it be great if you could change him to be exactly as you need him to be, of course, but you can't, so why bother even trying. It's just wasted energy on an argument that goes nowhere.
Sometimes you just need to vent. Being a mother is the most difficult thing in the world. I'm so sorry you're feeling shit about this. I hope things improve for you soon. You didn't ask for suggestions so I won't offer any, but I hope you make it through too and if it helps, know my house is messy too, borderline dirty tbh around skirting boards and under sofas, but I just tell myself it won't be like this forever and try to carry on.