Virgochick:
You handled it perfectly! You made your point and showed up their rudeness without being rude yourself. You have absolutely nothing to apologize for and if your boss asks you to, then he is being unreasonable.
As far as that woman being a nurse, well so was Nurse Ratchet! Thank goodness you weren't her patient when you were in the hospital. Did you really have a hysterectomy or did you say that just for effect?. If so, then you are a really quick thinker as well!
As far as rudeness in general is concerned, in my entire life I have encountered rude sales people maybe half a dozen times. The one year I worked in a retail store, I had rude customers on a daily basis. Some people think that if you are in the service industry, you are their personal servants to abuse as they wish.
Cog