Will you let someone getting married to apparently nice person who otherwise is a serious criminal and you know it?
That's just an example, btw.
You mentioned the element of enjoyment so I replied in that perspective. I have seen such people who think that they are justified to disclose someone's secrets among the whole public but even in worse circumstances noone has given them the right to reveal anything to anyone.
But the example you gave is exceptional like if someone is going to have loss and you are sure about it then you should help him/her out by telling him/her the truth.