Do you know what this medical condition is called?

There was this woman on the Titanic that stayed really calm when everyone else around her panicked. She spent the last moments tidying her clothes, neatly packing her things, putting make-up and so on. She gave her name (I think it was Ruth Something, but may be wrong) to this medical condition. It is when you get so overwelmed by reality that your body can’t cope with it so you go beyond depression, anger, fear etc to the other side, and feel nothing. I first read about it with regards to the people of Santorini, which is claimed to be the site of Atlantis. They apparently left in a very orderly and organised fashion, even though the volcano was erupting.