Best representation of PTSD ever put on film

This story isn't about PTSD, it is a story meant to be scary, and ultimately, uplifting, which it is, amazingly well.
But the fear and pain on the loved one's faces when confronted with it. The unpredictability and paranoia of the one suffering, and the tenderness coming from those who are trying to help get them through it (and the scary callousness of those who don't understand it, or who should be helping but only make it worse).

Man, this movie just hits me right in the gut, and makes me angry at myself for any of the times when I have met someone who has served and I have not said, "thank you for your service" with all the sincerity in my heart.