If you're privileged enough not to be threatened in that situation (ie you're not a younger woman, an immigrant, LGBTQ+) and it's not emotionally damaging to maintain the relationship, do. Be there, but be open about different and willing to answer questions. Either they'll be an ass eventually, or maybe, just maybe, you can show them the rabbit hole is just their head in the sand. Cult deprogrammers say over and over that the best way to get people to see reason is through personal conversation. But don't have expectations that it'll work all at once, or if they go back and forth in their beliefs. Unlearning worldviews is hard work.