Oh, I empathize with this so much. I was in a really bad bike-on-car accident a few years ago and it took a while for me to feel good about being on my bike. Here is what I did/still do:
One thing my therapist did tell me was that it is important to remember that I'm not doing anything wrong by riding my bike. You can't control everything in order to ensure your safety. But sometimes just remembering that I'm doing all the right stuff makes me feel better.