Lori, consider that for every dumbass comment like that, we get about a hundred like: "Bravo for you," "Wow, can I ask you a question," "Your very pretty/cute," or "can I buy you a Drink?"
I'll bet you she was a "Fundie Nutt," possibly very bitter, probably spends a lot of time hurting all sorts of people, and not just The Transgendered!
Yeah, I probably would have been flabbergasted, and at a temporary loss for words. But, what did happen was probably appropriate. If you had come back with some sort of cleaver retort, then you would have gotten The Tirade of obscenity, and A Huge Scene in a Place where you probably often shop. So, I imagine you didn't need that kind of Grief! If you ever see her again, walks in and wants her Dog or Cat fixed, just imagine The Sheer Joy of looking at her unrecognizing face, and knowing that you now have The Control! What goes around, comes around. Your A Pro, and I know would never do harm to The Animal, but you could just decide to torment The Hell out of it's owner!
Peace and Love, Joanie