And I understood that whatever I had walked into, it was larger, and darker, than a sister stealing a house.

Her reaction, in that basement, taught me more than any document ever could, and it is worth pausing on, because it is the moment I understood I was not dealing with an ordinary betrayal.

When a person is caught doing something wrong, there are, broadly, two reactions, and they tell you everything about who you are dealing with.

The first is collapse: the guilt floods in, the story falls apart, the person breaks down, because underneath the wrongdoing there was still a conscience that knew it was wrong.

That reaction, painful as it is, is human, and it is workable, because it means the person can be reasoned with, appealed to, brought back.