yeah. she's cheating on you with her ex.
her ex is the priority in her life.
it's a twisted form of unhealthy relationship where two people may be with others on a permanent basis but promises each other that they are the love of their lives. like a life time relationship. regardless of what relationships they may be in with other people... bf/gf, engaged, marriage. doesn't matter, they are to each other the highest priority.
how do i know? i've been in one, and let me tell you, it is SO unhealthy, like mandatory therapy unhealthy. feel sorry for her, though you're probably just hurt and pissed.
this was posted years ago, so i'm hoping you made the better choice and moved on. others who are in similar situations or, like I was, are the ones who are cheating on our spouses/significant others... it isn't worth it. all affairs are based on fantasy, no matter how special you feel deep in your gut that yours is....
the only way an affair lasts.... is so long as the fantasy doesn't burst to reality. but usually one person falls more than the other, so it's very very rare for it to work out.