This chapter definitely surprised me at several points, but Kurumi's stressed emotional state causing her to make a rash decision that she clearly later regretted was within expectations. The scene appeared to not go far, with Kokoro groping Kurumi's exposed leg, her chest through her shirt, and kissing her twice on the face somewhere. Not clear if on the cheek or lips, since the way the panel is framed. It might be clarified in a later chapter if/when Kurumi and Naoi kiss.
The thing is, Kurumi going along with Kokoro these past 2 chapters caused Kokoro to mistakenly think that Kurumi had finally accepted her. And for her to think that Kurumi would finally "go back to normal", when that was never the case. Kurumi was merely telling Kokoro what she wanted to hear to avoid another freakout, then later was trying to use Kokoro as a way to bury her stress over thinking that Naoi was with another girl. None of it was sincere. It all happened because Kokoro kept trying to push Kurumi into her ideal when that's not what Kurumi wants.
This was made very clear when Naoi actually showed up. It caused Kokoro to have the painful realization that none of her actions or anything that her and Kurumi could do together would change who Kurumi loved or who Kurumi intended to be. Kurumi looking away from Kokoro at that moment was what solidified that to Kokoro finally, which is what caused Kokoro to snap.
I don't see how Kokoro will get away with this. And I doubt she will. So much setup was done leading to this moment. Akane and Kurumi's mom enabling Kokoro's actions. Kurumi's mom's flashback advice about how one mistake could ruin someone's life. And it's possible that Kurumi not clearly rejecting Kokoro prior to things escalating this much is what was deemed to be that mistake. And of course, Kokoro trying to kill Naoi by strangling her is a serious crime. It's unclear if Naoi is even conscious by the end of the chapter. Given Kokoro's size and how she easily crushed Kurumi in a bear hug recently, it's likely she's causing major damage to Naoi's neck.
It's possible the character with the most control over how things play out at the moment is Kudou, since Kurumi's out cold, Naoi's status unknown, and Kokoro just had a serious breakdown. Given the flashbacks involving Kudou, I think it's possible she'll frame herself and maybe Naoi as victims, while completely throwing Kokoro and Kurumi under the bus. Kokoro for being the one to injure Naoi, and Kurumi for causing the friction between Kokoro and Naoi.
If Naoi's hurt enough to go to the hospital, then Kokoro's basically done. I have to wonder if that's why Naoi's dad was previously established as being so greedy. That he might try to sue Kokoro's family to get a payday for himself. Of course, he'd likely still leave Naoi to deal with the medical bills, which she couldn't afford. Which I have to wonder is a way for the story to strengthen Kudou's hold over her. Since then she'd need Kudou's money to pay off her debts.
As for Kurumi passing out at the end of the chapter, I think there's several reasons for that. She's been under an extended period of major stress. She skipped eating dinner and it's unclear if she ate anything much earlier that day. Kokoro noted her as being skinny, so it's possible she's not been eating right for whatever reason. Plus, Kurumi waking up sweat-covered in chapter 15 might've been an early sign of illness. She also rejected Kokoro's attempt to take her temperature. And Naoi noted that she looked pale. So, while everything was happening, Kurumi might've had the added strain of being majorly ill and feverish.
As for next chapter, it's up in the air. It could switch point-of-view to Naoi if she's still conscious. Or it could switch to Kudou if Naoi's unconscious. Though it's also very likely that it will stay Kurumi's point-of-view and have her wake up to the fallout of everything that's happened. If it's the latter then everyone's lives are likely about to get much worse.