Hello Miss Amber, and thank you for sharing your feelings with us.
Oh dear, life and death, you do have a heavy load on your shoulders. It is completely understandable that you were rendered so upset after finishing the documentary.Where does one begin to explain?
There is no sole method for coping with death, and it is an apt word for the process; "cope", because there is no "getting over" death, only a means by which you make accommodations for it. You make a place in yourself for the pains and pangs of death to reside.
The emotions you felt when you watched those men confront their final moments are very valid. It brought you face to face with the reality of your own mortality, which is never a very comforting experience.
The remorse you felt was not so much for the men themselves, it was for the waste of human life. Seeing anyone with such an irretrievably-ruined life would be distressing for and arise feelings of self-reflection in any human being capable of empathy. We are humans, and this life is the only one that we get. It is precious to anyone who understands this, and we are hard-wired with self-preservation.
To conclude, there is nothing wrong with how you feel. Valuing human life is one of the highest accomplishments in life, it is also one of the most basic.
I hope I have sufficiently answered your question, it took me a considerable amount of time to put this together.
Please keep in contact, and have a fantastic New Year!