It doesn't sound like things went horribly with your H.
He did exactly what you expected and frankly, exactly what a person in MLC usually does when presented with an offer like that.
It isn't that he has NO feelings left for you, he just doesn't know what or where they are right now.
He sees the pain and destruction this is causing, but feels justified in it to a degree, and the part he feels guilty about, well he is finding a way to put that responsibility on you.
Regardless of what he says, let him own the results of these current actions Irish. Don't accept responsibility for them.
Yes, there are things you are seeing in yourself, issues that need to probably really be worked through but you are NOT responsible for ALL of the problems and issues. No matter what your H or anyone else tells you. You didn't hold a gun to his head and make him get on those chat lines.
I really hope you know I am not trying to pick on you. I'm not Irish. I just want to see you healthy and happy. And to be honest, I think you have the strength to really face this stuff.
Your S, keep talking to him. About anything you are comfortable with. Take him to do things, water park, movie (I took my son to see New Moon when it came out, but it was the early in the day showing so no one would see him at a "girly" movie with his mom).
As far as being honest about what your H is doing, with your kids, Irish, that is a hard thing for an adult to hear. About another adult. I don't know how it would make a child feel about their parent. What does the C say about that one?
"Acceptance doesn't mean resignation. It means understanding that something is what it is and there's got to be a way through it."--Michael J. Fox