This is when am actually useful (loves sad shit)
Sad/tragedy mostly yaoi some shoujo:
http://www.mangago.me/read-manga/ame_ni_niteiru/
http://www.mangago.me/read-manga/diamond_dust/
http://www.mangago.me/read-manga/cut/
http://www.mangago.me/read-manga/coponicus_no_kokyuu/
http://www.mangago.me/read-manga/let_dai/
http://www.mangago.me/read-manga/zankoku_na_kami_ga_shihai_suru/
http://www.mangago.me/read-manga/birthday/
http://www.mangago.me/read-manga/hai_to_diamond/ (not really tragedy but you should read if you haven't )
Behold my love for tragedy mangas
Look for some good tragedy mangas, would like shoujo or yaoi but other genres are fine