I couldn't read through all the posts, so if i repeat anything that someone else already said, i'm sorry. Think of it as confirmation. heh.
There are girls out there who are attracted to a guy because they are married. They find it challenging to try to get the guy to drop their wife. After that, they ditch the guy and find another challenge. Plus, this mistress could never fully trust you.. you're the guy who snuck around with another woman and then divorced your wife just to be with that woman.
Your wife may be plain jane, but from what you said, she sounds like she honestly wants things to work out. Of course, when she finds out you cheated on her, it may not work out.. if it does, man, you're lucky to have such an undrestanding wife.
Stay together for your kid. There's too many kids out there that have two dads or two moms.