What you are experiencing is normal. Happens to everybody who has some type of incident. I think the only way to overcome it is as briderdt says, through time and more good experiences.
I had a low drama 20mph low side in damp conditions. At the time I got up and rode home without worrying about it. But it had a HUGE impact in my head. Next time I took a corner in damp conditions I immediately remembered the image of me flying through the air! I had zero confidence in my grip level and I would start drifting wide on corners as I did not want to lean. For the first time I started knowing real fear when riding. Made no sense as my actual fall could not have been less dramatic. 6000 miles later and I still have problems in the wet. Nowhere near as bad as now as I was then but I am certainly very cautious when the road is wet. On the plus side I have not fallen off again and I’m sure my caution has helped keep me upright.
So my advice is to just keep at it and you will get better. Take it easy and never be afraid to call it a day if your head is just not in the game (that can happen even without a bad experience).
Good luck and keep us posted on your progress.