I too, for several reasons, can find negative/ confusing/ impromptu 'nasty' interactions with strangers to be very jarring. The effects can rattle me for days.

I usually try and calmly analyze, when I am able, the reasons behind why I feel so upset.

For example: Since this has happened, am I upset because I haven't really done anything to encourage their nastiness? Probably. It's confusing and unsettling to experience bad & completely inappropriate behaviour like this, unprovoked.

Is it because it's happened in public, and because of my history with a certain soulless relative, I feel extremely vulnerable to public humiliations, still, even at my advanced age? Very likely. (Same as above.)

Could my social anxiety be contributing to the length of time I feel so rotten and victimized by it all? Absolutely, yes. So give yourself time to unwind, and try and concentrate on other positive, healthy things 'til you get there.

There are other questions I probably ask myself, but you get the idea. Once I deduce what those people really WERE the ones responsible, and that THEY are solely liable for their strange & angry behaviours, I can relax a little and know that I handled it pretty well by remaining calm and neutral. This way, THEY end up with egg on their faces. I walk away looking in-control and unflustered (which, of course, I'm not---but no one but me knows that!).

It can take time and patient practice at handling pressure situations with grace and aplomb. A sense of humor, and a good understanding of your own rich, inner life can go a long way to helping us get through this stuff unscathed.

The world is a pretty stressed-out place at the moment. People can behave badly in an atmosphere like this.

Just remember: Whatever doesn't kill you, makes you stronger.