Well, there is one just like this called Warehouse (and of course there is Killing Stalking, but you probably read that already). Dark Heaven is pretty good, but it is mostly drama (with yaoi, of course).
here is a link to a list that I used to find some good psychological yaoi titles (I'm just too lazy to name them all): https://www.mangaupdates.com/showtopic.php?tid=38870
on mangago.zone you should read Harada's yaoi mangas she makes really sad and messed up ones
Hogu Hagyeongsu is just pure sadness. I kinda regret reading it. But not that much.
Anybody know other manga that's low-key messed up like this (like yaoi, kidnapping, rape, psychological horror, etc)? Hogu Hagyeongsu is one example, Warehouse is another. There was one more that was pretty bad but I forgot its name.