Frank... a word of advice...
So far, this story has been limited to this forum and Marathon Investigation, but it's only a matter of time until there's a slow news day and it hits the major media. Previous course-cutter threads here have lasted for two years or more. This is not going away. You need to nip this in the bud right now before it gets any worse.
I'd suggest you call Derek and tell all. The cover-up is always worse than the action. Get it all out. Don't make excuses. Say something like...
"I did it first in ( whenever ). I got away with it. It was a rush. So I did it again. And again. I have no excuses. I apologize to everyone and I've asked Derek for advice on what I should do to make amends."
...and then shut up. No excuses.
Right now, your friends, associates, patients, and neighbors don't know about this and, frankly, most of them couldn't care less. In fact, many of your nonrunning friends would blow this off if you told them about it. Everyone makes mistakes. Just own up to it.
That could change if you make it worse by digging in your heels.