I'm really confused as to why this would suddenly happen. Does anyone have a similar experience or any advice on how to overcome this.
I'm really sorry to read that this has suddenly happened to you.
As to why, a professional psychologist may have some theories, but very few here will be able to answer you.
Unfortunately, someone else's experience will not be a lot of help except to provide inspiration (if it's ultimately resolved) or perhaps not.
Our brain is a remarkably complicated and complex machine linked to everything else in our body. Something is triggering your reaction and you're reacting poorly to that reaction.
The trigger may be that you were running late and stressed before you departed, or that you spoke to someone before you were due to leave - and your brain is connecting that to the crash (or maybe 100,000 other things).
The fact is, that trigger has been activated and is now a "sore point". It may calm down, perhaps for months but it can flare up again.
The danger, is that it can spread into other areas of your life.
Giving up won't deactivate the trigger.
Pushing through will probably make it worse.
Taking a break may reduce the sensitivity of the trigger (whatever it may be) but it will most likely remain to be reactivated in the future.
My strong recommendation would be to contact a doctor for a psychologist recommendation, or to seek out a sports psychologist. If you're a member of a cycling club they may well have contacts to help.
It's not much different to a young child who has a bad experience with one dog. If ignored, that child will fear dogs all their lives. If treated, not so much.
Best of luck!