General rule, for good or ill: usually, girls want to talk about things, no matter how embarrassing it might be. That's where your roommate's girlfriend is coming from, if you ask me. It really wouldn't hurt (other than your ego) to talk about it with her... it will only make you appear more humble, communicative, and open to talking about sensitive things, which are all
in most girls' books.
But it's up to you, really.