Just keep reminding yourself what they are and why

No, you don't have to be nice to them on "family holidays."  That shit is over.  But do be aware that they are probably armed.

Digby:

The mostly white, evangelical Trump base believe he can do no wrong. And there are a lot of these folks. It appears to be around 40% of the country who identify that way. And I firmly believe they are motivated almost entirely by their loathing for the eggheads, the racial minorities, the non-Christians, the city folk, the uppity women, the immigrants. They do not think they should have to share this country with anyone who isn't like them.  In fact, they are livid about it.

But I think we also have to acknowledge that right wing propaganda on television, radio, and social media has fed these impulses and created such an insular information environment that many of these people simply don't have any idea that Trump is failing on an epic scale. They think the only problem is the "fake news media" that is sabotaging him. They are living in an alternate universe in which only good news about their idol is real and the bad news is all made up. As far as they know, everything's going great!

I do have them in my immediate family.  But even before Benedict Donald, we banned discussion of religion and politics at family get-togethers.  It's a tense and stressful peace, but peace nonetheless.