"Even in this situation - in which I am only suffering because I have a false belief, and for reasons directly related to that false belief - I still think my interlocutor is very much in the wrong."

You wouldn't be suffering only because you had a false belief, another reason would be that you weren't sufficiently thick skinned to decline to be offended.

"Someone makes Nazi jokes around me, or says that everyone who died in the Holocaust deserved it and went to Hell, or something equally offensive."

At this point I would ask myself "Of what consequence is this person's opinion to me"? And I'd instantly conclude: None.

To cause me real pain a statement would have to be justified in my own judgment.