Your dear friend called you racist. So what? Who cares?
This is a site for issues of logic. While this question has some logical implications, I see the underlying problem as psychological.
Keeping with logic for the moment, he made the proposition that you are racist. He who makes the proposition, bears the burden of proof. Rather than get all flustered, as your statement suggests, ask him for proof. Starting with a definition of racist. But, unless you are skilled at the Socratic or Boghossian methods in getting the other person to use logic, you will lose the discussion.
Therefore, I’d use his statement to have fun, and reply:
Christmas is coming, so I figure you are compiling a list, checking it twice, of how much much you think I am abhorrent, abject, ableist, abominable, atrocious, awful, bad, base, beastly, bombastic, breedist, contemptible, cultural appropriator, cursed, despicable, detestable, disgusting, fascist, fascist-fascist, fatist, fatophobic, foul, full fascist, grim, grody, gross, gun nut, hairy, hateful, heinous, hellish, homophobic, horrible, horrid, ignoble, ignominious, ignorant, imperialist, Islamophobic, Jesus freak (even though I am an atheist), loathsome, lousy, low, lowdown, MAGA, mean, narcissistic, nauseating, obnoxious, odious, offensive, phobic-phobic, repellent, reprehensible, reprehensible, repugnant, repulsive, revolting, semi-fascist, semi-fascist, sexist, sexist, shabby, shameful, sleazy, speciesist, stinking, stupid, terrible, transphobic, transphobic, Ultra MAGA, unworthy, vile, worse than fascist, wretched, and a downright rotten person.
And, I almost forgot Lady Hillary’s deplorable.
That’s okay, too. You missed my grave faults.
So, adding your minor unfounded and impolite pejorative simply makes the rubble vibrate. I don’t sweat such spittle-sprayed slurs because they are not dreaded micro-aggressions, but mere insignificant grains of sand on the world’s beaches of life.