Arsh, just saw your update. I really seriously don't know what to say about your husband. Did you or the mediator ask his reason for wanting to keep living there? Maybe he feels guilty about leaving the kids or it makes more financial sense for him?
If you can go to a counselor yourself that might help a lot in getting input based on someone who can see and work with you regularly to figure this out.
Have you tried to do any investigating to see what your husband is doing when he's not at home? If you could find out where he's going maybe that would provide a clue. Until you know more about what triggered all this it's hard to know if you should keep doing DB in hopes of saving this or if it's a lost cause.
