Can someone recommend me a really sad manhwa/hua/ga?? It can be bl, gl, straight whatever....

hmm! don't know if it will be sad enough for you but you can give it a try
http://www.mangago.zone/read-manga/orange_marmalade/

Thank you!

10 years where i loved you the most
1866
Stigma
Itou-san
Life Senjou no Bokura

Idk if you have read this one but it is ridiculously sad
http://www.mangago.zone/read-manga/10_years_where_i_loved_you_the_most/

Also this is a new story I discovered it also had sad vibess
http://www.mangago.zone/read-manga/ways_of_parting/

december rain

also if you can find the manga for this one
https://myreadingmanga.info/anime-winter-cicada-fuyu-no-semi-ova/

I found it
http://www.mangago.zone/read-manga/haru_wo_daite_ita/ ( in vol. 5 Winter Cicadas )