Unless you're running a pretty sizable operation selling copyrighted material, copyright infringement is a civil matter, not a criminal one. The only person that can really fuck with you is the owner of the copyright and, again, that would only be a civil suit. Also, you've wayyyyyyyyyyyyyyyy overestimated the morality/efficiency/power of the police lol.
Just delete all your cookies and history + torrent files and leave all the music or games or whatever you torrented on there. Unless he was wearing a wire or something, I don't see how he could prove that you torrented all that stuff and didn't buy it.