mild agoraphobia

Dear Healer George,
Hi. I am fifty one years old. I feel terrific, I take natural supplements daily.
I have had this weird problem for about 20 years. Most of the time when I go somewhere in the car with my husband I become anxious. In fact, it was so severe on trips that he bought an RV which worked great. But in a car just going out to eat or shopping I often get anxious. If I am going somewhere alone I Usually am fine. There have been times that I have been Extremely anxious when alone in the car, though, especially twice when I had to drive downtown to pick up our puppy at the groomer's. I had a slight feeling that the dog would be just dying to get out of there and I was Very upset. And the puppy does whimper for me when he hears me.
This started many years ago. I THINK or Assume it is from my ex husband starting pointless arguments in the car before I split. I had an experience with him back then, sitting in the back, where I started thinking I couldn't stand him; that I hated our life together.
And I think possibly this may have started this silly thing.
I don't have thoughts that start it that I'm aware of most of the time. It just seems to come from Nowhere for no reason. I've tried deep breathing and thinking pleasant thoughts but nothing works once it gets started except for XANAX.
I wanted to know if you have any suggestions. thanks very much!