Musicelf, I have been through what you are going through now when I was I truck driver myself in the early 1980s. It is difficult but the situation can be overcome with appropriate action.
Just to give a quick background on my accident, the 32-ton truck that I was driving was hit by a car that had lost control on a bend. The nineteen-year-old driver of the car has spent his life in a wheelchair since that day, while his father was killed as a passenger in the same vehicle.
Although the accident was in no way my fault as the vehicle tachograph demonstrated, I could not get the incident out of my mind, and driving other trucks in the days following could well have resulted in me having another accident that would have been very much my fault.
After those few days I eventually reported to the depot transport manager that I was going off sick and the reasons why. However, that evening I had a phone call to say "report to the depot next morning as the senior company driving instructor would be there to see me".
He talked to me in regard to what had happened and then we went out on a normal journey, with him instructing me as if i were preparing to take my driving test all over again. Having to get my driving up to top standard for an HGV vehicle took my mind away from the accident and restored my full confidence in my driving abilities.
The instructor also had been trained to handle situations such as my own, and he would on numerous occasions in the week he was with me, ask me to go through what happened from a few minutes before the accident to the moment the emergency services left the scene.
He would stop me as I spoke asking "what would you do different if you where there now". The answer would always be "nothing", and he would say "exactly none of it was your responsibility, therefore you have no responsibility for the outcome of the incident, you could even now change nothing".
That week of re-training completely restored my confidence in my driving and myself and i returned to normal working and driving once again. The key was very much in having that instructor get my driving skills right back up to top level, and having someone face me with an in-depth analysis of what happened and convince me that nothing could be changed or can be changed, and life goes on.
Therefore, Musicelf perhaps you could consider taking some driving instruction once again with the objective of once more getting your driving skills up to the highest levels, for while doing that you will have your mind taken off the accident while you are driving and back on the road.
Also talk ,through the incident with someone else or a number of others. Do not keep it all knotted up inside you. Let it out and you will realise that nothing could be changed or can be changed, and perhaps like me your life will return to normal.
Hope this helps