Pornography Addiction

My fiancee has an addiction to pornography. I do not know if I can deal with this or not and so I am unsure about whether or not I should break of our engagement. We have had a problem about this issue in the past and I eventually told him that he needed to get help or I was going to leave him and so he did arrange to get some counseling with our pastor who is also a counselor and he is still going to see him once a week. I am happy that he is trying and I believe that he is making a real effort to get better but I found out yesterday that he has found some way to override the porn blocking software on our computer and has been looking at it again while I am doing shift work in the evenings. He can spend hours and hours doing it.

I do not know what to do. I love him and I beleive that he is trying to change and I want to support him, but based on the evidence I am not sure if he ever can. What I really want to know is if he cannot control his urges to look at porn will he also not be able to control his urges to have sex with another woman if the opportunity ever presents - or is this a separate thing. I do not really understand sex addiction. Can a person be just a porn addict or are they a sex addict and that also looks at porn? I guess I am fortunate that our physical relationship is still OK and the porn has not affected his desire to be with me physically.