Red Mansion - beautifully toxic bl
Checkmate - unhealty but healthy at same time
reverse thinking - super toxic
Codename Anasthesia (forgive my spelling)- definetly toxic but i dont know about the depth, i dropped cause it was not my type...
i dont exactly know what codependency means so see if it fits ur taste...
mmm codependency (ㅅ´ ˘ `)♡
https://www.mangago.me/read-manga/form_of_sympathy/ psychological angsty slowburn
https://www.mangago.me/read-manga/radio_storm/ dystopian horror
https://www.mangago.me/read-manga/black_mirror/ psychological horror

I am looking for unhealthy, codependent or one sided codependency and toxic relationship mangas/manhwas!!!
ive been getting into this concept lately.. hehe ╮( ̄▽ ̄)╭