So now that it's that time of year again in the US, what are some tips and tricks for dealing with that one relative who goes on about the same bullshit for hours and won't shut the fuck up?

You know, the guy who's been having that same angry conversation about the same fucking thing he's been obsessed with for the last 5 years and demands that you take his view while going on long monologues and then immediately interrupting anyone who tries to get a word in edgewise? And then goes into a weeks-long suicidal despair if you try to leave the conversation? Any way to deal with that?