Clearly and without question the woman is a despicable monster. Thats a given.
However, the attitude shown toward her was totally different from that of the man. They both commited for the most part the same crimes - posing as other people, lies deceit cheating etc etc. Her extra one was to be posing as her daughter - vile, his was murder ffs. He was presented as a poor wronged man rather than someone that commited a terrible act in cold blood. And the implication was it was more her fault than his. If she had indeed been the 18 year old she pretended to be there would have been no witch hunt, she would have been an extra in the story not its main purpetrator. I suspect what horrified more than anything was the suggestion that a woman rather than a girl had powerful sexual urges and no self control. The article below sums it up - to read this would suggest that the woman who told despicable lies was more responsible for the murder than the man that pulled the trigger.
www.examiner.com/interpersonal-relationships-in-national/talhotblond-portrait-of-a-mother-from-hell
I hope the woman rots in hell - my point is that the revulsion is all aimed at the woman who pretended to be a younger woman, not the man that pretended to be a younger man and then commited cold blooded murder