Thanks LA... I would add one thing, from a guy's perspective...
Don't make it about "right or wrong". You need to understand it is what it is. You don't have to agree with her. You don't have to like it, want it, or feel she is right. If you're like me you will have a hard time getting past the "moral rightness" of tearing a family apart for things that can be fixed. Of inflicting pain on your kids so things are better for her.
This moral righteousness will consume you. This isn't about being right, it's about being. You can stand in judgment of her if you like, but you'll be standing alone.
Look at her and see that she is hurting. Why is she hurting? Who knows, but she is. And then ask what can you do to help with the pain? But realize you can only control you.
So your wife may not be "right". But that's not the question. She is what she is and where she is, is where she is. It all has a very Zen feel to it, btw.
I know I find myself now repeatedly defending my W from people who feel a need to have moral outrage. My mom, my co-workers, friends of my W... all who just don't understand what she is doing or why. Who see the pain being brought on the children and are angry for them and angry with her. I've done a lot of "glass houses" and "cast the first stone" conversations. My W is where she is. Being angry or vengeful sure would feel good, but doesn't get us anywhere. We all have our own crosses to bear.
Married 6 together 8 Me:38 W:31 second marriage for both SS12, SD10, S6 Bomb: 9/8/11 (day before our 5 yr ann) W moved out: 2/18/12 D final: 11/12/12 Share S 50/50. Spend as much time as I can with SS & SD