Actually, it's this girl who sounds more as if she doesn't know what she wants than you. Oh, yes. I'm going to say drop her and move on. Not meaning to offend, but she sounds like an easy **** for any guy who's thinking with his dick. For a guy who thinks a little more north of his waist, like you seem to be doing in this case, she's not. I'd bet that screwing you would've put her at risk of having an emotional involvement. Which is something I'd guess she can't or doesn't want to deal with.
"Guilted into" having sex is, probably, the most lame excuse I've ever heard for bumping uglies. If this girl can't help but be dragged around by her pussy, you don't want her in your life in any form. Not even in IM. Ignore her. Altogether.