The Sword of Satya

Satya is one of the main tenets of Yoga, it is so basic that all the other precepts of Yoga build upon.  Well, all but one:  Ahimsa.  Therein lies the difficulty for it is easy to speak the truth with no regard to its impact upon others.  The question then is this:  Is it better to remain silent and allow others to believe a lie or is it better to speak the truth knowing it will harm those who hear it?  Further, which course will do oneself the least harm and is such a thought even acceptable considering Santosha?