I'm sorry to hear that Clogs!!! But good on you for trying to help others through your experience. Interviews can be very daunting, especially ones with questions about difficult situations, but as you said, there's nothing wrong with taking a few seconds to think about what you have been asked.
One thing I found helped me to answer questions (and many of you probably know it too) is to think STAR
the Situation, the Tasks involved, the Action you took, and the Result. Even if the result was bad, show them how you learnt and what you did (or would do) the next time...
There's plenty on the internet about behavioural interviewing, read as much as you can, and as Clogs said, there's nothing like practising (out LOUD) what you want to say, it really does help with the nerves as you have some idea of what to say and how.
Good luck all!!