Well.... usually any I bump into I immediately want to forget so I can't really help you there.
Try http://www.mangago.me/read-manga/funouhan/
And the manga "Berserk". Someone recommended it to me and I regret looking into it.
Doreiku Boku to 23-nin no Dorei
Tori Maia
Found this list http://www.mangago.me/home/mangalist/38849/ maybe you will find some here
Try Itou-san by Kuraka Sui. It's somewhat disturbing and bittersweet.
http://www.mangago.me/read-manga/itou_san_kuraka_sui/
There's also a prequel to Itou-san called I: Episode 0.
I feel like reading a fucked up story, can be gorish bloody with lots of violence,pain, sadness etc...
Any genre is okay bl,gl, etc...
Someone recommend me their fav?