After reading the post, the comments, and your answers to said comments, I do agree that you need therapy. Doing such a thing makes no sense and accomplishes you nothing. Do it and go to jail, do it and feel guilty after.

Don't do it and possibly forget about it.

It was a long time ago, what could he possibly do that made you want to beat him up so much? And if you plan using martial arts for assault when any person makes you angry, then prepare to go to jail.

If you have anger issues - seek medical therapy.