Mentally troubled after doing cocaine one time... a year ago.. still haunts me

I already posted about this but I think I wasn't being that clear...

Basically, I tried cocaine. No big deal...

The problem is that since that one time I felt like something changed in me... Like people could tell I was someone who consumed... It began to intrude in my mind, the idea of being "marked".. People would touch their noses everytime in the street. .and that made me very ashamed. To this day, things have only gotten worse.. And I keep thinking to myself this bad stuff... Literally is buried deep in my subconscious,.. I can´t even look at people in the eyes anymore. I feel like I wasted my life.. and that I don´t deserve the good things of the world. Im unable to enjoy practically anything. anytime I feel good or appreciate something the thoughts automatically make me disconnect from the joy I would have had If i didnt make that choice... and that just feeds the whole thing.. Is there anything i could do? anyone had any similiar experience with regrets like this? Also , I can´t stop projecting it... like , anytime i meet someone the first thing that goes through my mind if the urge to know if they ttried cocaine or not... even though this sounds ridiculous.. I just cant get rid of it.. and I feel that is something I will suffer for my whole life.. Thank you for reading.. Let me know what you think.. greetings from Argentina