If someone has completely forsaken mitzvah observance, or continually transgresses a particular mitzvah whose severity everyone is aware of (for example, eating pork), you are permitted to shame him for his misdeeds.  Since he has not merely succumbed to temptation, but knowingly and willfully transgresses G-d’s mitzvos, you are allowed to tell others about his misbehavior.  You should also not give him the benefit of the doubt.  ~ Guard Your Tongue