There is a time to be truthful and say everything as you believe it to be. And there is a time when silence is the better choice.
Truth may set you free but if in setting you free you cause pain and suffering to someone you care, then better I suffer in my chains than cause such harm.
I have never subscribed to this religious and righteous idea of truth. I now believe that there is no universal truth and that it is different for each one. Not even murder.
The other day, I held my tongue and kept quiet. What purpose would it serve if I defended my position? The other party was not rational, being in the throes of anger. Answering and pointing out the obvious would only have inflamed the other party more. The incident was not that important anyway. There are fights where it is better to just walk away. And let the other party think what he likes to think, believe what he likes to believe.
But there will be encounters when you need to stand your ground. I think it is simply a matter of choosing your battles. Truth can be your weapon. Use it wisely.