On the verge of pornographic addiction

I am a 23-year-old campus student. I have a loving boyfriend whom I have dated for a year. I have a major issue, which I think if not sorted out, will destroy my relationship with him, yet I love him very much. I have a laptop and a modem, and I have been accessing pornographic sites. It began as a joke, but I think I am now almost addicted. It is affecting my feelings for my boyfriend and I think it is worsening each day. What do I do to permanently quit?

{Tracy}