Oh Scott, I sooo feel the way you do at the moment. I have 2 little girls and think "I'll be fine, but the girls will hurt and always be missing one of us" if we divorce/even separate. I can't believe H is so far gone that he doesn't care about this either. My girls, oh my girls. I don't deserve to be away from them for just one night, they shouldn't have to miss me at all. Now, I am thinking (er, obsessing) ahead because we are still living under the same roof, but I need to grasp in my head this might be a reality.
You can be the solid parent your girls need. If anything, this horrible situation has made you a better parent, more aware of their feelings and putting them first more than ever. Innocent faces..innocent questions..innocent everything. SO hard.