I cannot watch anything on the topic of the Holocaust. I know I am missing some incredible films, but I just can't. I find that subject so horrifying that I get really overwhelmed and depressed.
Anything about really horrible war atrocities gets me. An excellent film that had me feeling like someone had punched me in the gut emotionally was The Last King of Scotland. I found that film not just horrific, but incredibly sad.
If you are just talking tearjerkers, Dancer in the Dark made me cry and cry!