Hilchos Rechilus, chapter 1, section 7

Rechilus is certainly forbidden if keeping quiet will only bring you insults, and no loss of money.

Remind yourself that because of this, in the World to Come you will be counted among those who love Hashem, and your face will shine like the sun. As the sages say (Yoma 23): "Those who are insulted and do not insult back, who hear their shame and do not answer… about them the verse says (Shoftim 5:31): 'And those who love Him are like the sun going out in its might.'"

This is even more true if you are insulted because you keep the mitzvos. See what we wrote at length earlier in the Laws of Lashon Hara (1:6).