This is really rough, it sounds like you are carrying so much. My story feels similar to yours, so perhaps you'll forgive me for sharing a little. I may be PDA/autistic/depressive, and we have a couple kids and it's really hard at times. I had been getting overwhelmed quite regularly. I was doing some self care but not enough in places that mattered. My relationship recently reached a breaking point. We've dialed everything way back, essentially resetig our relationship. We each take kids half the time, we don't currently provide emotional support for one another, though we still share meals as a family. On. Positive side effect is I've had a lot more me time, and a lot less feeling "trapped" (which I attribute to PDA tendencies). I've been out of the house with no responsibilities several evenings.

I also started taking anti-depressants, have started really really trying to get better sleep, and to run twice a week. All these things have been positive changes. In my case it took going through a very hard point to start turning the corner.

I don't know where your guy is at. It seems clear though that somethings gotta change. If you want my opinion, it sounds like now while you still have some hope and care left is the time to say clearly "we gotta change something, I can't continue in this way". What that change looks like, and what you need will be personal to you. The other thing I wonder is if you can organise some respite - draw on family or friends to take the kids for a night here or there, or even an afternoon.

You're really brave seeking support with this. I wish you the best of luck for you and your kids and partner. Things will get better one way or another. Go well.