You haven't been "dating" her you've been her fk buddy who wants to date her and she date you and be exclusive. But that's the last thing she wants from you. She's still there only because she thinks you're going to snatch away the job you offered her (which you should do. You certainly don't need her stagnating you in this trance she's got you in )
Stop being a sap. Seriously. You keep starting threads about her when instead you should be backing away from her so that you get over her and you'll then be open to meeting a chick that actually wants you and isn't a manipulative shrew.
The minute she thinks you're onto her, she insults you so that you'll lose even more self-confidence because of her and her selfishness. She's using you for a human dildo and a job. Stop lowering yourself to be with her. Really... stop it now.
“The willingness to accept responsibility for one’s own life is the source from which self-respect springs.” ~Joan Didion