I have a similar problem with an immediate family that's ultra-liberal & my religious community. I try to ignore the idiot posts from the former while concentrating on the latter.
I've had to "unfriend" a few, liberal or conservative, who were just too annoying, period. One person showed a picture of her rash; another complained constantly about her (now ex-, I wonder why) husband. It just got to be too much.
Free Republic has it right, which is why I love it here.
I am just on FB to laugh. Too many idiots who can’t spell or use proper grammar. I don’t take any of them seriously.