'If no woman ever slept with a married man, then no men would ever have an affair.'
Um, yes.
And if no married men slept single women then no men would have affairs.
Affairs are horrible things (don't do it window!) but this evil other woman attitude can be more than a little pathetic. If a man is married he should not be coming on to other women full stop. He needs to take the blame, he is committed.
(That said of course the OW is partially responsible)