The thing is, you can't have what you want. I know that's brutal.
You can decide to stay together for these economic / family factors - but even then, you don't seem to have a clear plan re your property & mortgage. I'd be really worried about this at your ages.
Then there is what you do going ahead after the DC are older.
I suppose you need to agree with H a plan for both your futures?
However, I can see no way you can indefinitely stay sleeping together in the same room, bed, when you have very firmly realised you no longer love each other or want to be together.
It's one thing if you have niggling doubts. Another entirely if you've reached that point of certainty.
I remember that dread when I knew my marriage was over, abusive in my case. I'd tiny DC, one a newborn, and I couldn't see a future. The marriage did end, and 10 years later, life is much harder than I'd expected. I can't see a clear financially comfortable future, tho superficially I look like I am managing. I try hard not to look enviously at siblings & friends who have now begun to reach some financial equilibrium & have options I don't have.
It's really hard. But I don't think you can continue like this or if you do, you need a clearer plan