Hello, i've tested years ago a visualization method to lower my social anxiety. I consisted mainly in fixating on the person in front of me, on his forehead and head shape, and strongly concentrating on him instead of me. It worked , that including reading a bunch of psychology and personality disorder books, they all cured my anxiety.

The problem now is that i've somehow developed this form of OCD that's killing me from the inside.
It's not psychotic and it goes like this, if i encounter/meet some person i know i have unfinished business with, like someone from work, i keep on fixating on them even when i'm home. It's like i constantly think about their face and it pops up in my mind like a zoom impulse. I don't know how to describe this pulsation, but it's horrible. No hallucination or anything, just a visual thought. The exact visual thought i've exercised for years when talking to people on the spot, except that it won't go away now.

I feel devastated, please teach me a trick to derail this thought. Thinking of something else works on the spot, but sooner or later the visualized person keeps popping up in my head constantly annoying me like 20 times/day.

It comes from a single person at a time mostly, until i stop seeing them for a while or forget about them, and i encounter another person. It's both males and females and there is no sexual/romantic attraction btw.
Thank you in advance!