My sympathies. Ignorance, especially willful ignorance, can be absolutely exhausting to deal with.
Don’t focus on that. Just remember that Friday is probably the last time you’ll see him alive. Try to steer the conversation towards pleasant memories. Make the conversation about his life, not current events. Ask him about his childhood, his first car, how he met your grandmother; stuff like that. People like to talk about themselves. Plus, it’ll keep the conversation away from politics.You might even learn some interesting family history!