Here's what I would do...
1) File a police report and get a copy of it.
2) Get his automobile insurance information and file a claim against him.
3) See a doctor and get checked out.
4) Consider retaining an attorney that specialized in bike claims
5) Replace your helmet.
I probably would have called in to work and said I'm not coming in or I'll be late, I was involved in an accident and have to deal with this now.
The number one person to consider is YOU. If the vehicle was damaged, it may be boderline repairable, but it would be evidence that it was involved in an accident. If it got fixed out of pocket, then the evidence is gone:n "No officer, I don't know what he's talking about, my car is fine, I was near that area but I wasn't involved in an accident...maybe it was a car that looked like mine." or it could go "No officer, I was there, are you sure you got the right car? I wasn't even driving that day, I was at (insert location at the other side of town) at that time." Don't delay. get it done.