Correct the historical sequence they have in their minds. Always emphasize that fascism emerged as a popular reaction against a decade of communist terrorism. That German communists had twice tried to overthrow the liberal Weimar government before the NSDAP even existed. That Lenin was just across the border slaughtering Russians, first cutting off their right arms to prevent them from performing the sign of the cross.

Always correct "liberals are the real fascists" nonsense. Firmly but politely suggest they should simply call communists communists. Explain that the thing they're calling "fascist" is more a hallmark of communist tyranny (this is especially apt when the thing is censorship). Then explain that Antifa isn't confused about the directionality of things and that the contrivance of "antifa are the real fascists" only serves to obfuscate and misdirect people who are under attack.