***I desperately need advice on how to deal with confrontation with someone who in the past hurt you greatly? I don't trust this person and they ruined me emotionally for a time period however it is out of my control for this person to be in my life.***

Going through a really strange/difficult time right now (will explain some specifics below) that requires a face-to-face confrontation which is something that really triggers and scares me. 

**BACKGROUND:** There was a situation with one of my roommates ex-girlfriend in the past where she betrayed my trust and decided to air out my personal information amongst our roommates including my boyfriend. This ended up ALMOST compromising my entire relationship. Which obviously hurt and betrayed me. 

Said roommate has decided that after a full year he wants to be with this girl again, who I clearly am still uncomfortable around. I tried establishing a boundary within our home to prevent her from being in our home and around me because it makes me really uncomfortable and anxious however, I can tell that it can potentially put strain on their relationship. I feel guilty for being a roadblock and it has now come to a place where she wants to confront me and sit down one-on-one to explain herself. I feel like regardless, I am going to be uncomfortable in this situation and will have to compromise myself and my boundaries and am scared of how I am going to deal with it. 

How am I supposed to deal with the confrontation with her without completely shutting down? The thought of it makes me start to feel outside of myself and very anxious, I really don't want to disassociate or have an awful conversation because of my own issues. I tried telling her and my roommate that I was extremely uncomfortable with her presence and do not trust her intentions or her as a person and would rather avoid her all together but **apparently that is immature of me. (SORRY making jokes here)** 

***Seriously, ANY HELP OR ADVICE FOR ANY SITUATION AFTER A FALLING OUT WOULD BE APPRECIATED.***