Stalemate by Aoyama Toomi is good.
If you don't mind straight one:
http://www.mangago.zone/read-manga/flowers_of_evil/
I love how your question completely demonstrates the downward spiral...
I didn't think I'd like....because its....but then I read.....like half of my favorite things to read started out this way
Hmm....if you liked "Not Equal" then i highly recommend this one -
http://www.mangago.zone/read-manga/haikei_niisan_sama/
It's not smutty or yaoi like Not Equal, but the emotions were portrayed in an extremely beautiful way. Hope you like it :)
You know I didnt think i could like a incest manga, because you know its INCEST, but my friend said " Read Not Equal and relax, manga it's just fiction,that doesn't mean you approve incest in real life" so I read the motherfucking manga and OMFG that was one of the best manga I ever read !!!!! And now i want to read more, but i only find the cliche ones,I want one that deals with the fact that is wrong, that shows the suffering of the character.
So please if you know how should I said ,a realist story about incest please tell me !
Thank you very much(▰˘◡˘▰)