How important is a lack of secrecy in judgments of wrong doing? Obviously, no-one should be found guilty of a crime and punished for it, without being informed and making their case. What about e.g. 'infidelity': is my wife permitted to decide I have cheated on her, without telling me? What if she then sets out to destroy my life, based on false accusations: how in turn shall we judge her?
Secrecy is not inherently immoral, but it can be very dangerous and harmful if it is used to conceal wrongdoing or to manipulate others. Secrecy can also erode trust and intimacy in relationships, and create a sense of alienation and resentment.
Lying, on the other hand, is always immoral, according to my view.
Therefore, I would argue that a lack of secrecy is very important in judgments of wrongdoing, because it allows us to confront the reality of our situation and take responsibility for our actions. I would also argue that honesty is a virtue that we should cultivate, as it helps us to align ourselves with the truth and the good.
As for your example of infidelity, I would say that your wife has no right to decide that you have cheated on her without telling you or giving you a chance to explain yourself. That would be unfair and unjust. She would also be wrong to set out to destroy your life based on false accusations. That would be cruel and malicious. She would be violating your rights and dignity as a human being, and she would be acting immorally.
However, I would also ask you to reflect on why your wife might suspect you of cheating on her. Is there something in your behaviour or communication that might have given her that impression? Have you been honest and faithful to her? Have you shown her respect and love? Have you neglected or taken her for granted? Have you tried to understand her feelings and needs? These are some questions that you might want to ask yourself before you judge her too harshly.