Not clear to me what happened from your post. ??
I am curious did you unhook the clip instead of triggering a safety release on the leash?
Did you accidentally or intentionally unclip the clip attached to the harness BEFORE the safety release higher up the leash line?
I hate those stupid carabiner style clips, they are no good for kiting.
Attached a picture of a better one, that used to be more common.
Regardless, Sorry for your pain. Best wishes with the recovery. Thanks for putting up the picture, it's a service to us all.
We're always only one random event away from accident.
@ tomatkins - I think they are popular cause they are cheap and look "strong," but alloy and no swivel. Whole sport has marketing disease.