Not sure I can help you much as I have not had to go through this myself, but I think you have taken the first important step in analyzing why you crashed. Once you understand that you can take steps to make sure you don’t do it again. Also, I would think going back to the basics such as parking lot practice might help. Regain your confidence in your ability to control the bike etc.
I would only go on solo rides. That way you can ride within your comfort level and even call it a day if it is just not happening for you (I’ve done that myself). Maybe even take the BRC again, or sign up for extra riding instruction. The way I look at it is this is a skill that is going to take years to master, so I am in no hurry to force it along. I ride within my comfort zone but that zone gets bigger as the months go by.
As to your question as to how many other have incidents to learn from, I think we all do, all the time. You don’t have to fall off to learn valuable lessons. Early on I was nearly hit by a car and it shook my confidence. By posting about it on another forum it forced me to think about ALL the reasons it happened and I realized it was a chain of events (just like they teach in MSF) that started long before the near miss. By understanding this I was able to change my riding habits and regain my confidence.
If the fear does not go away then it might be that bikes are not for you, and there is no shame in that.