Tell her that she needs to talk to a professional about all her relationship and insecurities issues and you are done being a " back up" because that's how it feels to me .. Shes likes keeping you in the loop. What do you get out of this situation?

Borderline? Sure maybe??? maybe she has 7 other mental illness diagnosis? or none at all ? Or maybe she is just a lousy human being and needs attention and assurances 24/7

I see nice guys like you get sucked into the vortex of an EX girlfriend far too often on here ... Seriously just let her go deal with her drama... Enjoy life and find other healthy well adjusted adults to hang with