I’m sorry you’re experiencing this right now. It can’t be easy especially since you really want to be there and start this job. Are you able to hire a driver from a reputable company in the closest city to drive you there for those 3 days? If not, what if you told your employer that your car needs repair and can’t get there in person and as another person suggested to request Zoom? If there are no other options, then you may consider telling your boss exactly what you told us. I do believe your sincerity would come across and you may be surprised how understanding people are.

And major kudos for you to attend counselling to help your anxiety. Changes may take time but at least you took the first step.