My theory is that Diane really does hire people to kill Camilla, but Camilla survives without Diane knowing it. She has no memory of what happened, nor of Diane’s suicide, and so she imagines her as a way to keep living. That would also explain why the aunt is still alive. When Diane suddenly disappears, Camilla finally realises what truly happened. Now the reason the director is forced to choose a different head actress is because the cowboy knows about…