((((((((((( LoosingControl ))))))))))))
I'm sorry to hear of your car wreck. I can only imagine how scary it was for you. I'm so very happy that you were able to walk away from it.
My youngest daughter has been in a couple of accidents, one really bad one a year ago July where she too was lucky to walk away. She told me that she doesn't have an issue in a car if she herself is driving, but when she is a passenger, she has a lot of anxiety and PTSD. The accident she was in over a year ago, she was driving, the other accidents she has been in, she was a passenger.
You don't say if you were driver or passenger....but I guess in the grand scheme of things it doesn't really matter. What I would suggest is if you have a T, discuss your feelings with your T, they can help you get through your anxiety and possibly help with the nightmares. If you don't have a T, I would highly recommend finding one that can help you with the trauma work needed to help you feel more comfortable.
Remember, this happened only a couple of days ago. It's fresh in your mind and on your mind. Give yourself some time to work through your feelings and memories and be kind to yourself while doing so. Deep breathing really helps when you are feeling the anxiety rise and grounding yourself to your surroundings by noticing colors, objects etc.
I hope this passes for you quickly....

sabby