It is difficult to predict what will happen next. I think Woojin is more or less starting to change his attitude towards Wooyeon. If at the beginning of the story he took the opportunity and r@ped him, then after the last hypnosis, when Wooyeon was sick, he admitted that he felt disgusting. I can't say for sure, but I don't think he'll go back to hypnosis, at least not towards Woojeon. Maybe he will apply it on Junghwi. I've read different stories, in some of them the psycho characters do evil, lead a righteous lifestyle and do evil again. But there are also those who become more humane as the story progresses, I hope Woojin is that hero.
Disclaimer: I am aware that in real life his place is in a mental hospital, but this is a bl manga, where r@pists can turn into adequate people...
FYI, for people who hated "WE started this...", it is a wrong translation, I read in in original. Literally "It started as something fun but it isn't fun anymore". Maybe I'm a little too into it, but I don't want others to think that Woojin considers his brother responsible for his own choices. Also I liked that in chapter 42 he said sorry, maybe not for all the things he should feel sorry about, but at least it's something, his first appology
https://funbe293.com/%EB%82%98%EC%9D%98-%EC%88%98%ED%95%98
People! Here is the link to all the chapters in this manga. For now there are 27 chapters already! So if you are as geeky as I am, use the google translater's camera to read it properly.