I have PTSD and have a lot of memories coming back from over 15 years ago. I numbed myself for all that time but my treatment providers (I went IP at a PTSD program) told me that it always comes up eventually. If it wasn't this "competition" with your friend, it would have likely been something else.

I'm not going to give you tips on numbing it out again. What you need to do is find a therapist who specializes in trauma or a trauma group in your area. You can also read up on DBT and emotional regulation (sounds like you already know with your counseling experience). The previous poster's suggestion of writing a letter to your 11 yr old self is spot-on. I did that in IP and it helped tremendously.

You may also benefit from some short-term anxiety meds until things calm down. I wish you best of luck in dealing with this. You don't want it haunting you off and on for the rest of your life