I'm sorry to hear your situation has taken a turn for the worse.
I feel like in my own situation, everytime things start looking better, something changes in my wife and she takes a huge step forward. I have a feeling the OM plays a large role in this, as very little changes in the house.
She has even told me things like "now that you are the husband i always wanted, its too late" - I take that to mean, she has found someone else and thinks he's better.
Astimegoeson is right - the OM is always a loser in some respects. Men with things going on and things to offer do not chase Married women with children.