Who is Katherine Wentworth Sexton from Deception Point and what is their importance?

Katherine is Sexton's wife and Rachel's mother. She died years ago in a car accident after being left home alone on Thanksgiving. Sexton cheated on Katherine repeatedly, which is part of the reason Rachel and her father do not get along. Katherine also saved Rahel's life when she was a child, rescuing her after she fell through the ice. It is this incident that has made Rachel so afraid of open water.