His eternal unflappability, E.J. Dionne, suggests several angles by which you "might coexist" on this 17th day of national mourning with your loud, ignorant, inebriated, Trump-supporting brother-in-law.
You can try reminding the subliterate brute that the presidential loser actually won "by something like 2.5 million popular votes, which in every other kind of election would just be called 'votes.'" You can agree that the Rust Belt has been "flattened by technological change," about which the winning loser won't do a damn thing. You can agree that "Democrats and liberals did not do a good job of addressing the estrangement of white working-class voters" — a "good job" being, presumably, that of blowing demagogic claptrap up their underemployed skirts.
You can empathize with the rabble-roused deplorables (tweeted one astute observer: "Not all Trump supporters are racist, but all of them decided that racism isn’t a deal-breaker") for wanting to "hurl a wrench into the gears of politics" by supporting a flagrant con man, whose wrench will of course hit them just as hard. You can "accept the criticism that the Clinton campaign didn’t devote enough attention to offering a clear economic vision," although the vision she did possess was never covered by the ape-obsessed media.
You can gently express concern that the president-elect intends to use his new office, "his power and influence," to self-deal and further "enrich" himself. And finally you can warn of Trump's unflinching proclivity "to punish his opponents and isolate a critical media," now through the "misuse [of] government’s power."
To which, I would add this. When all of your rationality fails to crack open a glimmer of self-awareness in the impenetrable skull of your loud, ignorant, inebriated, Trump-supporting brother-in-law, you can, and should, forthwith take the table's gravy bowl and dump its contents right over his thick head.
You will so enjoy the ride home, for you will indeed have had the happiest of Thanksgivings.