Oh Priscilla, I am so sorry. {{{hugs}}} I went through the same thing last year when a little black dog was hit right in front of me as I tried to coax him to me. The driver took off and I was left cradling the dog with massive head injuries.
I felt sick to my stomach with sadness for over a week and my pupsters were worried for me.
You did all you could. It will take time to get over that horrible feeling.