The purpose of stress interviews is to check your assertiveness and ability to handle pressure.
To handle stress interview questions, your main goal is to stay calm.
Don't take the bait. As best you can, shorten and simplify your answers.
Don't be afraid of repeating yourself – especially if the same question is asked repeatedly in different ways.
And don't be afraid of standing up for what you know is right.
You were invited to the interview for a reason, so don't let them push you around or make you question your capabilities.