You'd already fucked her by that point, so who cares? If you'd had a condom for round two, the proper response would have been, "Yeah, and you're about to be full of myself, too," as you thrust in.
She was probably just trying to take you down a peg to make herself feel less slutty since you were a one-night stand. I'd be careful about calling her "basically a whore," though. Unless you bartered for sex, she wasn't a whore. A slut, maybe -- not that there's anything wrong with that -- but not a whore.