http://z.about.com/d/movies/1/0/e/d/7/justfriendsposter.jpg
Seriously, if you want it to work out, you really need to take a step back from it. Don't come off as an emotional pussy or she'll leave your ass real quick, or act even more like she did before until you leave her. Just stand your ground. If she goes off like that, just blow it off like it's absolutely nothing. If she keeps getting worse about it, just act like she's just another girl and you can find someone better.
BTW, any friendship to relationship (or vice versa) I've been in or witnessed has never worked out well. I'd start working on my game with other girls, if I were you.