Ah, OP.
I could've written your post and all of the replies you sent, too. In fact, for a little minute I had to check I hadn't written this while I was sleeping!
I think the only difference for my and my DH, is that he's been recently diagnosed with adhd. It doesn't show as you'd automatically associate with adhd, but it has answered a lot of questions we have had over the years about his behaviour - poor financial control, disorganisation, not great with IT (struggling to learn new things) - just a couple of examples.
After 20 years of this building up, I am learning a lot about our family dynamics. Yes, like you I am a bit of a martyr, but having a chronic illness start this year, I have learnt to slow the hell down and take some me time.
Interestingly, one of the PP mentioned about guilt tripping, and the associated behaviour a such as sighing, ignoring, etc (DH does this when I take 'me' time). The posts here have really made me think more about our relationship and I appreciate their thoughts.
I don't have any answers, apart from saying - you have to make some changes. You have to show your kids that mommy has to have time on her own. EG- on a wknd day, take yourself out of the room and lie on the bed for 30 minutes with a magazine. Announce to DH you're taking half an hour out as you need some space. Alternatively, arrange a coffee with a friend while he has (his own) kids for an hour.
It's also really worth talking to him about it. Sit him down and just open up. It doesn't need to be aggressive and finger pointy, but it needs to be honest. We have tried to be more open and honest in our relationship in the last few months and it has definitely helped. I have listened to some great podcasts recently that have made me realise I'm not on my own and I'm not going mad. There are decades of unhealthy patriarchal/familial attitudes, standards and beliefs that make us who we are, and I'm not going to feel bad because of who I have turned out to be. I now know I don't have to remain being that person.
If you want to pm me for a further chat, please do. You're not alone OP ❤️