God fucking shit it breaks me heart to hear that. I'm so sorry for your loss.
My mom is quite pro science and my dad became a bit spiritual, conspiratorial and anti-science, but none of them were hit that hard. I feel like I'm in the opposite situation where I technically can try to convince him to change his mind every time I see him but he is extremely stubborn and there's no way. In fact it will make him dig in deeper and the only way for him to change is by himself.
Fuck this timeline I want a reroll.