We're all mad because his horrible past and circumstances shouldn't excuse his awful actions. He's undoubtedly the villain, but his abuse and awful behaviors towards shinitani and especially haruma aren't justified because nobody loved him. It's not okay to kidnap your crush's sort-of-bf and his sister and coerce him into fucking you on top of his sort-of-bf because he doesn't love you, even after you paid him to go on dates with you, and fuck you. I feel so bad for him because he's made bad choices due to his shitty circumstances and he's for sure someone who has gone through a lot of trauma, but that doesn't automatically make everything he did okay. (For me personally, it was the fucking on top of haruma scene that really sealed the this-shit-is-too-much-now-even-if-he-has-a-sad-past).
Regardless, you’re right he’s not in his right mind, but he seems pretty clear minded anyways. He kidnapped shitani’s sister, stole someone’s love, etc. it doesn’t excuse his actions just cause he suffered.
A murderer kills someone cause they are not mentally good, does that justify they hurt someone? No. If you think so, something is wrong with you.
Sudo is a bitch, that’s probably the nicest thing to say. He fucked with Shitani in front of Kikuchi who’s the real victim here.

Uuuh why everyone hates sudo? He is obviously mentally ill, he suffered a lot.. yea he may be an asshole but can you really blame him? He never received affection