By his "moving out for his health" the day to day connection that you two have WILL be severed.
It is not insane to think of the financial implications... but how will it be helped by his having two rent payments, two sets of utility bills, two houses to keep food in and pay for cleaning supplys for, etc... Plus furnishings.
I would perhaps look into using that money that would be spent on those and perhaps find a friend that will watch the kids and pay them for it.
You guys are going thru what most call the "7 yr itch". Its a time period that you look around you and think about the what ifs... what if I HADN"T got married when I did... what if I lived where I had wanted to when I was 18... finished school, got THAT job.... etc.
You can change your routine at home. But his moving out will not change his routine. He will still be working insane hours. And since you said he'd still have the kids how will he be getting more rest? It will be harder on you because you will not have the support he gives you at home when you are both there.
His moving out is the easy way... Marriage takes work.
Perhaps even having someone else watch the kids for just a few hours will enable him to sleep and go to a gym...