you've really got to watch out for yourself on this one. let her know exactly where you stand, but don't be pushy, this really is her decision, shes bound to have enough pressure already, without more being added
personally.. i'd be wanting to have a long talk with her. find out if this guy is somebody she can see herself having a fullfilling relationship with. i would suggest against propaganda tactics, ie: commenting on how much you dislike this guy, telling her how wrong he is for her, and generally trying to sway her in any way, it never works and usually ends bad.
its obvious you want to pursue a real relationship with this girl, and yet you told her your fine where things are.. why not be honest? let her know how you feel.
if it were me, i'd suggest the idea of removing the sexual aspect from your relationship, and working towards remaining friends, at least until she doesn't have this looming over her head. then, you would probally have a better chance of keeping your friendship, even if she does end up back with this guy.
if shes sane, she's stressing out in a way you can only imagine. ask her what she wants from your relationship. should things be put on hold till the storm clears? should you break it off now, and save you both a lot of pain? whatever she wants to do, try and support her. a little understanding and empathy can go a long way
just try not to get your hopes up, be yourself, and try to give her as much friendly support as possible
i am of course, not an expert however, so do what you feel is right