well the girlfriend part is easy in my eyes. just ask yourself does she respect you? like real respect? if yes than don't worry but if you have to think about it drop that relationship.
now for the jacker, really two ways to go about it. first, i keep the motto "the best revenge is living your life right" close to me. if ya have promising endeveurs up your way i feel its best to stay out of scandalous circles altogether and focus your energy on positive movements, even when it comes to payback. the second, find where she lives send outta town goons or girls to fuck her shit up majorly, take her shit, and fuck with her sense of security big time. l