Why are you stating this in the most favourable way possible for her? A non bias person would say that's a very strange note.
Saying you killed on purpose is "exploring" I don't agree, its disturbing at best. And a confession at worst.
It clearly was a very disturbed note. Either way, we also had experts who said some have died of air being injected.
I never said proof of guilt, its called evidence, and its used to built a case with other evidence which then the jury can decide. And circumstance evidence can be used in a case.
People have been charged and put away, when there has been no direct evidence before.