Grief. How do I get over it!?

Marissa
Long story short, my fiances friend died in my arms after being struck by a drunk driver while he was on foot. I used my training from being in the medical field to figure out the best way to care for him but going 80 I know he had no chance. I have been so distraught since it happened may 31st. We are laying him to rest tomorrow and I just want to be able to go back in time and tell everyone NOT to be on that road. Today we had a viewing for him and they had to reconstruct his face. I couldn't look at him for long. Maybe 5 seconds. I felt so numb. I didn't even know this man honestly. All I know is I wish I could have helped. My heart breaks knowing someone lost a son, a brother, a friend and most importantly some little boy lost his father.... I just heard about what the coroner's report stated and everything I assessed that night was what the examiner said. Broken hip. Fractured skull. Bruise above hip. Spinal injury. The one that was the worst is on his face where he landed on the windshield of a car. It dented the left side of his face and left a huge gash. I haven't gotten to speak to anyone about it and I think if I had a best friend or a counselor it would really help. I just need someone to reassure me that I did everything I could. Everyone left him after it happened. Left him to pass alone. I couldn't let him die alone. I wanted him to know people who cared about him were there to make him feel safe. I can't get the sight of him out of my head. Someone talk with me?