wow..... so wow...
This is one of those tragic things that I hope I never suffer.
Not to insult your soon to be ex-wife... But what kind of person takes that kind of action without at least discussing her marital issues with you? Seems to me that no matter what she says, its still a sad excuse for her actions. You have nothing to worry about, if anything I would say get a P.I. or something equally ridiculous (the whole situation is ridiculous isn't it?) and get PROOF. You don't need to file for divorce only for it to become her word against yours. She is the one who breached the agreement of the marriage, so she gets nothing.
Thats all.
Again, I'm sorry, but knowing this kind of stuff happens is still a slap in the face.