WHAT IS IT WHEN A MAN HAS ACHILD OUTSIDE HIS MARRIAGE?

What is a women supposed to do when she is in love with a man that has gone outside of his marriage and has a child by another women? and what if he doesn`t even know the women it was a one night booty call? what is the difference if it is a relationship other than marriage? what should a women do if her whole life was built with this man , what if she found out while he was incarcerated and the other women knocked on her door?should she except him back and help with the child or should she get a divorce and move on? where can a women get help to deal with this emotional break down that she go`s through ? does counseling really help? what kind of damage is done? is there a chance that she will take this hurt into another relationship? will this effect the children/ what if the child is a girl?