Dear TheLastSlice ofBread~
"Does everyone replay each conversation over and over again?"
I rather like your giving those anxiety-based thoughts another given name, it is not you after all, but another influence impinging on you. Naming it is a reminder it is not you.
Unfortunately Nancy is not amenable to reason, If you are like I've been then no amount of reassurance, no amout of logic will stop the endless replay, one which places you as inept or at fault.
There are two main tools I use at the time - I'm not taking here about lifestyle, therapy or meds -which are all long term - but just dealing with each instance as it occurs. Pardon me if you are already aware of these.
The first is exercise, with distraction, getting you out of the environment where you have been static and thinking in circles, giving you mind the task of dealing with new surroundings and the sensations of bodily activity.
The second, to break that chain, or place me in a calmer mood, is to use the free smartphone app, Smiling Mind. It takes practice but it's worth it. There are exercises there for even the most inattentive and preoccupied of minds, and it works.
Having a partner you can say you are in the grip of 'Nancy' is pure gold. It creates a harmony that the unexplained actions will never do and at the same time is inclusive, your lives are closer.
I also am in that happy position (though she is just as likely to tell me when I'm in that state) and can offer perspective, calming my more catastrophizing mental preoccupations.
Actually you do 'get life', your poetry is so spot on and shows that at that level at least you go get it more than many.