Wrong turn

So there is a friend I chat with the time. Since 4-5 years.
We always had long conversations. About deep and 'boring' subjects, off-course with our limited knowledge and understanding.

He has helped me a lot, I have helped him a bit. He was like my elder brother.

He would criticize me very frequently, but only with a goal of mutual learning. We have spent 100s of hours debating on various things.

But suddenly, everything changed:
I was upset by the news of a violent mob lynching of 2 sages in my country.
There are multiple reasons for me to be upset.

I told him about that, and he suddenly went hostile. Accused me of being a hyper nationalist, accused me of saying things I never said, and kept using the word 'bullshit' in every sentence.
I kept asking proof of his accusations, while I later realized that only he was going on on a keyboard rampage without even reading my responses.

I didn't see that coming. This was a shock to me because I never thought that he was not a person who would do that. He used to be a good listener, a calm, and intelligent person.
_______________________________________________________________________________________________________________________

Next day, he sends me messages like nothing happened.
Sends me informative videos and asks for my opinion on that.
Unable to decide, I don't respond.
He chases me to steam, asking me if I want to play a game or not. And "are we not talking or something?"
_______________________________________________________________________________________________________________________

I can't feel normal like before. This thing will always bother me. 
Things can't be taken back to normal, like nothing ever happened. 
Even if we "talked about it". 

I am not sure how to deal with it.

I realize how something like that can make you re-evaluate your perception of the person and maybe things just can't go back to normal, but you have been talking with the person for four or five years so it seems that it could be worthwhile to talk to them about it. Maybe nothing will come of it or you may find a reason for their flair up.

You probably hit a sensitive area for him, or he was just having a bad day so needed to let it out on someone. I'd probably just not bring it up again and move on. I have people I just don't talk about certain topics with because I know our views differ too much for a productive conversation. Or if it does bother you, ask them for their thoughts/why they reacted like that.