Dont do anything too harsh or even risk getting caught. He obviously knows unpleasant people and will just make your life shitter. As has been said plan it out, make sure noone knows anything, spray paint "twat", his house phone number, or "rapist" all over the front of his house. Then a few days later or how ever long it takes just do him over. Break his nose, give him bruses, black eyes, cuts. Then get a "clipper" lighter and burn smilies on his forehead and cheaks but do it cleanly. The scars it will leave will make him look like a complete tool If where you live is anything like where I live everyone will know whats happened to him in 2 days tops. That should piss him off for a fair while