I too have made the hard decision to separate, and I stayed for years longer than I should have, just to give the kids the stability of a two parent household. And yes, dovex3, we did the counseling, therapy, etc etc.. church based at that. After 4 months of therapy the pastor essentially gave up, as my ex was unwilling to modify her behavior in the slightest way whatsoever.
There comes a point when you actually can do more emotional harm to your children by staying in a destructive relationship than you can by separating. At least this way, the time I spend with my kids is quality time, comforting and nuturing and not fighting every few days with my ex, so they grow up thinking thats what "normal" is.
Dovex3, you do manage to offer (believe it or not) one piece of advice, at the end of your diatribe, that I totally agree with though..."have all the answers ahead of time when he talks of where to stay, who will he be with, school, friends, church etc etc. These question go long above the fact that you (both parents) will tell the child the you love them no matter what."
Children are full of questions, and divorce is an upsetting time as it is, so do all you can to have what answers you can anticipate in place, so that he doesn't realize you are quite likely just as confused and scared as he is.