I also just completed the NTR route (hate it but I'm a completionist) I'll paraphrase this by saying I DESPISE NTR, but as much as this route infuriated me, filled me with dread and made me cringe, the writing on it was an absolute marvel. It was so gritty, and emotional and well written, it made for an enraging, but also engaging story. I felt real emotions playing through it and was shocked by the outcomes and twists in it. Phew. I hated every minute of it because of the content, but the author really made me DESPISE the characters involved, it painted such a vivid picture! When the MC raged out and that heavy guitar music suddenly kicked it the hair on the back of my neck stood up and I was "OOOOOO THEY ABOUT TO GET IT NOW!" But I was genuinely worried about L the whole time and it was painful to purposefully take those paths. Very well written, this author is an absolute genius writer. I usually crap on NTR as a genre, I can't get off to such things, but the story... man. If it was a TV show it'd be a hit. The drama of it all was phenomenal. Excellent work.
I started a new game for an evil character who was near that part, so I just fast forwarded to it and made separate saves to get there and play through it. I didn't want them to be permanent lol. Basically the dude all try to mind break L with drugs, and send you her "boyfriend" videos of it, depending on your choices on how to react to it, either she will be on her own in the final encounter and kills them all after a whole "there's a killer in the house" kinda scene where she hides in the house and ambushes them, when she finds out they're going to kidnap her sister to do the same to her, or you show up just after she finds out about that and stabs one, and absolutely slaughter them all like in the non NTR route. That's a 1st grade book report version of it.