wow...i am going to be reading a lot it sounds like - i do not think an affair is happening after seeing what it did to her family first hand - and she has told me she doesn't even have any sexual urges with or without me.
there is my "optimism"
you know sometimes people say things just to be nice, women who lose sexual urges for their husbands still have sexual urges and it's usually for something "different", keep your eyes open