Hiding my friends comments and likes from public users without having to make my posts private

Hi my names josh I have an ex who has been harassing my girlfriend she doesn't want to make her Facebook private but we don't want the ex harassing family and friends by seeing her public posts and messaging whose liked and commented on them we've blocked her original account but she keeps trying to add her under false accounts we know they're fake because she got a request today from someone who started their Facebook on feb/28/2014 and had no friends someone please help the only thing she's figured out is to go back and hide each post individually but she doesn't want it to be where Noone that's not her friend can't see her posts.. is there a way to do this without going completely private..