The Heaviest of Burdens - R. E. Vance - Bog

Boyfriends suck.
But then again, I wasn't exactly the ideal girlfriend, either.
When Kat came home after almost dying - twice - to find her boyfriend in the arms of another woman ... well, it hurt. Hurt more than getting her head bashed in by an ex-angel.
Hurt more than getting stabbed by a dead god.
Kat is a big girl, and she'll get over it. Right after she messes with Justin and his new girl.
But when Kat discovers that Justin is being used by the World Army and is probably going to die, she needs to put aside her petty ire and work with Isabella to save the man they both love.
Who knew being human would bite so hard?