I sympathize, OP.
My parents have always done their best to isolate themselves from the world, which prevents them from making comparisons with others and realizing they're often irrational. Growing up, I was brought up to shun friends and family, which triggered my social anxiety.
Recently, even though I knew that politely telling my mother what I thought was not going to change her, I still told her anyway! It was cathartic, and after years of suffering it made me feel better. She thought I was crazy, of course. But now she cannot complain that I have not explained my opinions
The only thing that worked for me is distance - physical (a whole continent away) and emotional. When we visit, I try my best to not take the insults, un-constructive criticism and general nagging personally. It works for 10 days max, so I know not to stay longer than that!