Have you thought about doing a controlled separation? With guidelines?
Mary, my H and I are in a controlled S right now. We set up guidelines about child sharing, finances, house/car repair, dating, and a few other things before he moved out. It has been a real stress-reducer in my opinion. I don't have to worry about calling him when my heater breaks, he has already agreed to be responsible for that. We don't stress about money, we know who pays what. The only reason we change child-sharing is his business travel, which he has been pretty good at keeping off his days.
I don't believe the agreement will change the outcome of the S in any way, except maybe if we were fighting about these things I'd hate him. And I don't. Which I feel like is better for our kids. Anyway, it was the right way to go for me.