Why don’t you just mind your own business and let them live with whatever guilt they have? If they honestly feel no guilt just take solace in the fact that you’re a more mature person than they are and that you didn’t have to cheat your way to get into a top college.
Getting revenge is pretty juvenile at best, and spiteful and a huge overreaction at worst. Life isn’t always fair. Get over yourself and your vigilante justice. And honestly, what if they’re innocent and you cause their acceptances to be rescinded?