I really do not have any good advice for you, just wanted to say I know the feeling and eventually you will overcome this too. I think often times, as the years go by, things change and this feeling may become a thing of the pass, hopefully not replaced by something else. I used to have a terrible time in traffic, even a 3 minute wait at a red light made me crazy. There were times I nearly jumped out of my car and left it in the street at the light. I never did it, but I sure wanted too.
Do you have to drive through the city, can you take a little extra time and go around the city? I live on Long Island and there always seems to be a parkway that goes around the city. Traffic is horrendous here and I do fine. On a bad day, I just stay away from the areas I know may be backed up.
One more question. Do you take any other med for the anxiety? Xanax is good for the moment, but maybe something like Celexa, Paxil, Zoloft, etc may help you more.