You can certainly "parent together" with an ex. But you need to not still think you're in love with her for it to be anything but painful. But if you're really done -- really detached -- it's easy and far better for the kids.
Me: 46 W: 44 Married: 17 Together 21 D13; S10 BD: 03.03.15 (Not attracted to you) Almost 2 years trying, alone, to save marriage Status now: Divorced (effective 06.13.17)