i give you credit for trying to stop and wish you lots of bracha. Don't think there is anything wrong with yourself. As you can see on this website there are (unfortunatly) many people going through the same thing as you although you are showing a great effort to try to stop yourself. one thing i have bean trying to do lately is being honest with my self: why am i clicking on that link is it just for curiosity or for pleasure.
Please try to help your son! do what ever you can. you know the pain of what you are going through he is probably going through worse. i remember going through it while i was in my parents house and tried to stop but i couldnt ask for help. you have the advantage of knowing what your son is going through. please help him