I am not sure how the messenger work (although I am online often, I am behind the times to online communication). Can I assume that she knows that you can see that she logs on?
If so, maybe she IS hoping that you will finally respond. But careful. Like I said earlier, she will be nice to you until you ask about a relationship and then she will change her mind. It sounds like you are still interested in her although you may speak negative of her at times.
If you can't handle me at my worst, then you sure as hell don't deserve me at my best. ~ Marilyn Monroe