I'm sorry I misread your post, Blue

I re-read it keeping in mind that it was your anxiety was so terrible, and it was not a result of the Xanax. It sounds like you were suffering from a really bad case of "catastrophic thinking," which is common for people who suffer from anxiety

You don't have to decide from day to day (in advance) whether or not you will take the Xanax unless you know you will have to drive somewhere, operate heavy equipment (lol), or be particularly on top of your game for some other reason.
When the time comes, if you feel like you need it, take it. That's why you have the prescription for it