Wow, I would feel very hurt as well. People are so insensitive. And I agree it only adds to the stigma...

I would say ignore it if she wasn't someone you consider a friend. But since you do I say confront her. Tell her it hurt you and ask why she would say that. It may turn out she's not your friend after all, but in this instance I think it's worth standing up to her and telling her how it made you feel.