What makes you think you have to respond at all?
She calls you "ugly." That's her opinion. It's not a "fact." Therefore, there's no need to respond to it. She just stated out loud what she was thinking; it doesn't require a response.
Furthermore, no one said a man has to respond to every single thing a woman says to them. Me, I would have been like "whatever" and walked off. Plus, we already know most women are going to age a lot more horribly than guys are. I'd just assume she's going to eventually get ugly and keep it movin'.
