As a general rule, even if the victim's state recognizes defamation per se (which means tangible damages do not have to be proven) such an action is generally prohibitively expensive to litigate for the normal citizen.
Attorneys don't do these pro bono, and very few will take a defamation case on contingency.
Getting even isn't always what it's cracked up to be. Sometimes the best way to get even is to simply ignore the twit who's posted the offending material.

