First of all - glad that you're okay.

Second - let the kid's father rant all he wants - he doesn't have a leg to stand on! You were hit from behind - it's his fault whether he agrees or not. And you shouldn't be dealing with his insurance company at all - that's the job of YOUR insurance company. Just make sure that your company has all the details and a copy of the police report.

I was rear-ended by a woman who gave false insurance and residence info to the police investigating, so even tho my car was repaired and the bill picked up by my insurance, they never were able to track down the woman that hit me and collect from her.