I don't think we will ever know what really happened. I do think it was Patsy as others have said before, what happened between them is a guessing game. If it was an accident, why go to the lengths that she did to make it seem otherwise. It's a wall of secrecy that no one can get through. And others in the family have got to know, if it was her why continue to cover for her.
Today you could be standing next to someone who is trying their best not to fall apart. So whatever you do today, do it with kindness.