He has mentioned these views before, but more mildly, in a grounded and logical conversation between us. He didn't sound like he craves for an apocalypse (he's not even religious). I even agreed with some, although I pointed out I see the world way more positively as a total.

Very good question! I feel painful because it made me feel unsafe socially, and because it hurt the image I had about his character. Because it made me doubt how correct is my opinion of him. Also I thought that he's a bit more social adept than me, and that made me feel more relaxed when we were with people I don't know well. Now I'm going to be tense. Mild and peaceful social approaches are important to me too, tensions are the very last resort, and I thought he shared that based on what he said.
Questioning my relationship is probably due to the shock I've felt. It probably is just one off incident, I put my hopes on that.