Hi! I have A LOT in my 40 years of anxiety attacks. I have backed off a highway one time when I entered it and found myself in traffic. I threw it in reversing and nobles my horn and everyone moved to the side. I backed out about a mile. I have also stopped and called 911. Horrible, I know. But I know how you feel. I would panic so bad that my hands and feet would stiffen up so much I had to pull over. Not saying you will get that bad at all. Just saying I made it through that and drive with no problem at all. One thing to remember, its only fear and not rational thoughts. It's in your mind and you can change your mind. As much as you feel the anxiety has taken control, it hasn't. You and millions of others have driven down those highways and are completely fine. And even if the worst was to happen, You will still end up on your couch at some point. The anxiety and fear you feel is woody then adrenaline which means your body is working right. The only difference is that your unconscious is confused and you can change that by talking back to those feelings and thoughts. I began to use my time in traffic as time I could relax because I didn't have to be doing anything. I hope I helped.