OK, this one is definitely on the “Dear Abby” side of the communication spectrum. But given that the situation discussed here tends to sneak up without warning, it's a good idea to have a contingency plan. Smart communicators are prepared.
Here's the typical scenario: you're on your merry way when you suddenly slam into something which horrifies all your sensibilities. You discover, for instance, that your supervisor is defrauding the company. But, your supervisor is also your uncle. And there is no such thing as unseeing what you have seen.
You could travel along for years as a queasy rider, constantly nauseous, hoping that the situation just goes away and nobody ever finds out. In this scenario, you get the ulcer while your uncle sips pina coladas!
But there are more serious problems with the ostrich approach when and if the situation sees the light of day. First, you will be seen as somehow complicit, second, as time passes, your memory will let you down.
So, from a communicator's point of view, how do you handle such a situation? The questions really resolve down to what you say (if anything), to whom, how and when.
Here's the main thing: almost invariably, situations such as this have criminal implications. All too easily you can get wedged into a nasty place. A consultation with a well-recommended criminal defence counsel is often in order. Not only will they see the situation in a detached, logical way, but their discussion with you is covered by lawyer-client privilege.
It may also be wise to share the problem with someone “near and dear”, but only after you've taken legal guidance. Why? Because only with the lawyer do you enjoy lawyer-client privilege, so you will want your first guidance to occur in a fully safe zone. Even interspousal communication is not as privileged as many think.
It also goes without saying that if you need to make a public statement, consultation with a communication expert can be worth its weight in gold, especially if the expert is legally knowledgeable. For privilege purposes, it is worth considering having the communication expert retained by your lawyer.
The last bit of communication advice is that you must keep thorough notes, made contemporaneously, and with backup copies, all kept securely and privately. When you are called into question, or as a witness, many years down the road, you will be grateful that you have a “Comey Memo”.
In summary, keep your cool, get advice which is covered by privilege, and keep a careful record. Follow your conscience, but let your conscience be guided by clear thinking and good advice. And pray every night that this never befalls you.