Although my H's A was not nearly as extended, he did have a pretty involved EA (which lead to a brief PA).
Yeah, it sucks to hear. You're going to for awhile. The good news is, eventually that phase will wear off, and she'll be able to put it in better perspective. Unfortunately, right now she is still mourning that relationship. And, to be honest, she will need to go through that process and deal with it before you guys can move forward. Sucks, yes, but you will both be okay if you just have patience with this.
Also...at this point, it helps to try and do some fun, light-hearted stuff together. The new, good memories will definately help.
