If everything you say is true, the fact she is so obsessive about affairs and infidelity tells you its on her mind. It is likely her own guilt coming through. She may think if she can accuse you, it justifies her own errors. Your loyalty may frustrate her.
Divorce is ugly and unpleasant but so is what you are dealing with. Unless there's something we are missing, she could even have mental health issues surfacing. Her focus on money to support herself means she's already detaching herself and planning for her future, one that doesn't include you. I hate to recommend divorce, maybe a trial separation may be better, but you can still be a part of your children's lives and live positively even if that happens. They are suffering too; it's not likely that you're the only one suffering. It could be she's emotionally neglecting them as well.
Marriage is tough, even the best and strongest experience differences of opinions and periods of detachment. However, this seems like a trend that is spiraling into something uglier. Does she feel she gets enough attention from you? Could it be she's trying to goad you into an affair? Or that she doesn't feel desirable and wants you to be more demonstrative (which may be why she's seeking outside assurance)?
You might try focusing a bit on her value to you (you may have to set aside your resentment and justified anger for a bit to do this), to see if indeed attention is what she wants. Has your marriage (before all this) gotten into a rut? Sometimes when people get married, there's a large amount of excitement, and then the children brings excitement, buying a house, vacations, etc, but eventually day to day life settles down and can be disappointing for some who immaturely imagined marriage was all fireworks and passion. Small acts of attention and unexpected (even if minor) surprises can invigorate and regain some of the interest, IF both parties are hoping for that.
I hope you find some peace in this; life has enough struggles without dealing with them on the homefront as well.
