[Mel]

I think in an ideal world, many people would say "What should I have done in that situation?".
Why not use it as a learning curve instead. Obviously she was there to see if she could intimidate you and gage your replies to her questions and attitude, but if your interviewer was looking helpless in the situation he obviously wasn't expecting her actions either.
Don't let one persons actions put you off your goals.
After going through probably your worst interview it can only get better. If you kept yourself calm throughout the process, perhaps you passed her test, and also kept your own integrity.
In future consider looking past an antagonistic person to someone more reasonable and ask calmly, "Is this how I should expect to be treated if I were to get employed by this company?" If their reply is non existant or suggests that, "Yes this is what to expect", do what has been suggested and stand, excuse yourself, thank them for their time and exit.
That way you can be proud of your actions and maybe they will question their own.