For starters, it's as clear as anything on Earth that most of the reason Anthony even bothered with her is that he had the screw-ball fantasy of Liz landing on the woman with claws bared while howling "GET YOUR HANDS OFF MY MAN!!!!"
in order to pry her away from Eric The Man With An Actual Personality:
Also, she is a very bad and jealous person because she doesn't realize what a passive drone Liz actually is:
and how little the woman understands the harsh truth that she is the third person in their marriage:
Also, Liz doesn't quite understand how many people are ready, willing and able to stab The Evil Outsider in the back, front and sides:
Also, when the woman escapes an obviously untenable situation, her tormentor gets consoled by a doughhead:
while she gets defamed by someone who gets fed a diet of horse shit by a biased asshole.
Since Liz can pop up at any time and remind the poor thing how cruel and stupid the Pattersons are, it's kind of easy to cast her as an underdog.