true, the jealousy thing needs to be done with some finesse. i think she just needs to know that if your going to put it all on the line, she should be aware that your not gonna wait for her and that your not some backup plan to be there whenever is convenient for her. if she was never really gonna break up with her bf, then at least op has some other leads, but if she does then you won't have to waste much time waiting for her to do it. don't bang some skank the day after you put it on the line, but do make it apparent that your not afraid to seek a other classy women if she isn't ready to go for it.
seriously though op you have a really good chance of getting your ass kicked, and you might deserve it if you two hook up before she actually breaks up with him. it doesn't sound like the bf cares much, but i know if my girlfriend cheated (which i seriously doubt she would) i would break the guys fucking face.