I'd let it lay. You were honest with her -- that was the right thing. There's nothing else to say. If she brings it up, fine. If she doesn't then you shouldn't either. Talking it into the ground isn't going to help anyone. Don't feel guilty over it. It sounds like you did right by her, so if she feels used she's just going to have to deal with it on her own terms. The best thing you can do is to start putting it behind you.

And don't sleep with your friends anymore.