With the greatest of respect @NewPlumCat I think you are predisposed to reading posts in a negative way. Which is perfectly natural as a response to trauma.
But that doesn't mean that people are wrong.
You haven't been clear what you expected to gain from posting, but AIBU is a debate forum and people will have and share strong opinions. Which you invited by posting.
The vast majority have said as I have that you are responding to trauma and that you need to get help. That is not a criticism, it is a fact.
I too have been sat in stationary traffic when someone rear ended me at speed. I also had a 9 month child in the car with me. So I absolutely understand the trauma. That said you got off incredibly lightly. Muscular trauma will heal, you didnt break anything so actually the car did exactly what it was meant to do and absorbed the impact meaning you were not badly hurt physically.
But riling up against people suggesting you need to push through. Get back on the proverbial horse and carry on are not being unkind. They are being supportive. The absolute worst thing you can do is give up.
It was an accident, with the exception of utter psychopaths, no one gets in the car with the intention of ramming into the back of someone. I am.not saying the other driver wasnt at fault, from your description he absolutely was. But it was an accident.
You can chose to move on and rebuild your life or you can chose to curl up and cry in a corner.
What is your choice?