Accidently hit a large tutrle on the road today

I accidently hit a large turtle today on a country road. The speed limit was 55. I was behind a truck and suddenly felt something crashed under the center of my car I thought my whole exhaust system and gas tank was ripped out from my car. I looked in my rear veiw mirror and saw this huge round thing on the road about the size of a medium watermelon. I turned around and went back and was horrified to see it was a turtle . He had pulled out his head and feet and his shell looked like the top was shaved off there was a stream of blood coming down the side. I began crying and didn't know what to do. My cell phone was not chsrged. I didn't know where to get help or take him to get help. I started pannicking and then another truck went flying by and hit him and the poor turtle went flying in the air.

Cars were flying by and I had to get out of the way. I went back a few hours later to find him it was dark already and wasn't safe for me to be out on the country road by myself. I can't stop thinking of him and crying.
I was wondering if they could possibly survive this and since the top of his shell was shaved if he was in alot of pain and if there was anything I could have done.
I have never hit an animal before and I am really upset.
It was a accident and hope God forgives me.