Cant stop getting Anxiety when RP gf cheats IC?

I RP in SecondLife, and I have multiple characters, most of which are in relationships. One of my characters has a gf that is cheating on him, which sort of bugs me, so she usually wont talk about it when it happens. However lately, sometimes before and sometimes after it happens I get really bad anxiety, like a headache, stress, and erflies in my stomach. I cammed over once by accident and actually saw it happening and I think I had an anxiety attack. I dont say anything because last time I even said aything about my unrest about her cheating she bitched and threatened to break up the relationship. I need to know how to calm myself down when these anxiety things happen, Im still going to try to talk to her about it using one of her friends to sort of mediate, but still need help controlling this.