Its better that he looks at porn than cheat on you...unless, the porn itself is disturbing. (Bestality, or Children.) If so, turn him into the police.

Otherwise, if its the "run of the mill," sort of thing...do something better with your time and mind the business in which is RIGHTFULLY yours. You have ABSOLUTELY NO RIGHT involving yourself in the affairs that he chooses to have to himself. Not only is it disturbing that YOU FEEL YOU HAVE THE RIGHT, but, it shows that you have CONTROL ISSUES of which could be quite DANGEROUS.

You'd better lay off of that...because, FREE-WILL is a Universal constant in which NO ONE has the right to infringe and YOU WILL BE HELD ACCOUNTABLE.

P.S. - I'm not joking.