Sorry to hear that. I also have first hand experience. The best advice I can give is always be nice to her, regardless of everything. Listen to what she wants. Unless she wants to damage you (and only you will know about that - statistically unlikely) she will probably simply want to get herself out without damaging the kids. Anyone who has made that choice will feel very on edge, and is probably reciving inappropriate advice from pals, so (and this may sound mad) she needs you as a friend (or at least, an ally, and not a foe).
Separately don't underestimate the greiving you'll go through. My second divorce was one of the worst experiences of my life (the circumstances were somewhat unusual, I was skint and in negative equity, we had a child, the missus is a foreign national, you can guess the rest). For me, lots of talking with whoever would listen helped.
Best of luck, and please pm me if you want a chat.
