I believe there are two factors to consider: societal conditioning and self-preservation.

Sad to say, it is still much more acceptable in the U.S.A. for a woman to show emotions in public than it is for a man. You said that you cry when watching some movies and that you cried when Nelson Mandela died. Do you believe that you express your emotions according to your environment?

Being empathic, you should also consider that you emotionally shut down to traumatic events in your life as an act of self-preservation. Some people consider this to be in a state of denial. Only you can determine if one or both or none of these factors is contributing to your non-emotional responses to personal traumatic events in your life.

I wish you the best.