She "took" your man. Can you ever be friends with "the other woman"?

You are in a committed relationship with a man, and suddenly he develops affection for another woman. How do you respond? Are you angry at the man, or angry at the woman, or angry at them both? Do we really own the rights to each other's emotions? Can we really accuse another woman of "taking" someone that "belongs" to us? Women often see themselves as competitors for male attention, and sometimes become bitter enemies when they find themselves romantically involved with the same man.  Before we can even openly discuss the need for polygyny, we have to first learn to accept each others rights to have a loving relationship with the opposite sex. Sisters, can we all just get along?