go out and get a dozen cardboard boxes for her, ask her to start getting her things together and look for another place to live, tell her you're ok with this marriage being over if she doesn't care about it and if she doesn't care about the marriage or the kids, why does she need to live their with you & kids? She's living the single life, she might as well pursue a single life somewhere else, follow it up with this: "I can help you pack your stuff and help you move out, I don't mind" - if you do this, make it convincing, smile even, you have to believe it if you want her to believe it.
excellent advice. NOTE: boxes are cheaper at home depot then at u-haul.
I to lived in a self-imposed limbo land for too long, and the what I learned and the advice that I can give is the longer you allow it the harder it is to get out of it. The sooner you take control of this situation the sooner she is going to have to face the reality of her desicions. plus, you will not have to think about getting or consciously try to get a positive mental attitude, you will just have one.