If I were you i'd just laugh my ass off at her.
What the hell is legal refute?
Refute means (courtesy of my handy dandy always at my side Black's Law Dictionary): 1) to prove (a statement) to be false. 2) to prove (a person) to be wrong)
In the context, it makes no sense. I think she's just trying to scare you. You didn't make an actions or say anything legally that she can refute.
In other words, she's just bitter and blowing smoke out of her ass.
If it's another local, there's not much you can do.
But if it's a national sorority, you should send a copy of the email to their advisor or their HQ. It wasn't a very ladylike, gracious, or even civil email.
People need to realize you can't just sue for any damn thing you feel like!
Hybrid Mode
