@Elvarius Volume-wise, we are at the first half of Chapter 6 (Volume 2). Also, this is part 1 of the manga. Volume 4 (where Part 2 starts) will come out this summer. It has a different artist.
I didn't read the chaps in a row so I might be forgetting something, but you gotta think a little in the position of the MC too. You live with a "person" that is supposed to be dead and that can't be removed from the room and she can disappear when others visit. His friend just got killed and you see that person living with you eating innards that may or may not have been taken from your friend.
The beating was a result of not seeing any understanding of the words said before it so I don't think the result was that far fetched. Also being cramped to your apt for a week and not going to school etc can severely impact your sense of judgement. I do hope we get a new revelation soon though, because violence after the first beating is just flavor.
I decided to take a look because the cover looked interesting. Now that I have seen the GORE tag, I shall close this tab and reflect on my actions of not reading the description...
So assuming that Fujitang guy is the actual culprit behind the killings thus far, and the spider waifu is some sort of apparition, and didn't murder anyone...does that mean he just beat up a waifu for no reason at all? Yikes