Will gain overwhelming sympathy from all mutual friends and her family, making the husband seem like the bad guy. Will get custody of the children 9 out 10 of the times, even if she can't afford to support them...but that's ok, because the "justice" system will make sure that you support her like your still married, but she'll be sucking off another guy in the place you payed for.
Won't let your kids stay with you for more than 48 hours if you live more than 2 blocks away from her. Will do her duty to leak your secrets to all her friends, family, and every guy she sleeps with.
...oh well, where my check at?