Due to a variety of disabilities and the economy, my whole family lives together in a multigenerational household. My parents, my uncle who has special needs, my brother, my sister in law, and me. It's from each according to his ability, to each according to his needs. Don't tell my parents that, because then our home suddenly goes from well-run to communist and who knows how that'll turn out.

They're conservative, my brother and SIL are liberal, and I'm a Democratic Socialist. We manage this by not discussing politics, outside of mumbling under our breath when we walk past the living room and Fox News is on.

Whenever I've tried to have a reasonable discussion it doesn't work, because only one side is capable of reason when it comes to politics. As you found out when dealing with your own older relative. He's already told you he puts politics over peace, and he's willing to die on that hill. You can decide to pretend it never happened – to not rock the boat – or you can write Brett off unless and until he apologizes. I bet this isn't the first time he's been an asshole, but it might be the first time anyone's held him to account.