Company Trailer Breaks on Hwy... Negligence/Defect? My rights???

What is the name of your state? California

I am a CA resident and had an accident on Hwy 99 last Thursday.
Situation: I was behind a company truck, Ford F250, pulling a flatbed trailer that the company had assembled the night before. Driver was in fast lane, going approx. 70-75 mph. The trailer literally fell apart. It came apart where the neck of the trailer meets the bed of the trailer. The hitch and everything stayed connected to the truck. The trailer came off, traveled all the way across freeway to the slow lane, turned and came all the way back across to fast lane, hitting me head on. It's amazing that more vehicles were not involved. Damage to my car has been estimated at about $5000, but I owe $5800 on the car, and with as many miles as it has for being a 2001, it's only worth about $5600.

Questions: Is the company liable for product defect? Is it negligence on the part of the assemblers/driver? Am I crazy to ask to have my car totalled in hopes of settling enough to pay for a new car? And... after visiting emergency room for back pain and now seeking the treatment of a chiropractor... what I am entitled to for medical, pain and suffering, etc? This matter has been more emotionally draining and an inconvenience than I could have ever imagined! And of course, the insurance is trying to push things so fast that I am going crazy. They hadn't even called me with an estimate before okay the body shop to begin repairs. I called to have the body shop hold off on any work or ordering of parts until I seek advice.

PLEASE HELP! I feel I have a good case and that I have a right to be happy with a car that I feel will be safe and reliable now and in the future. Knowing that this "accident" could have been fatal, I want someone to be responsible for the stress and emotional damage it has done.

I greatly appreciate any advice you might have to offer.