So I just got this email from an in-law:

[Dear_Prudence]

32. Based on my own life,

It is possible that your relative was unaware of the depth of her vile views when he married her. Or maybe she has become more vile over the years. Or they have a bond based on her cooking, sports, horse riding, or whatever. My own husband is not hateful, but he is deep into conspiracy crap, so we don't talk politics. He is highly educated, but irritable and not persuadable. Some 46 years ago, I never ssked him "Who shot Kennedy?" Back then, it was most important to me that he loved animals. He still does. So sometimes I share DU pet forum items with him, and he responds positively to those posts. I never ever share other DU content. Maybe your relative is similarly situated. I agree with your non-response to her ugly email. She is trying to stab you with her hat pin, but you have wisely remained out of her reach.