Nester, I was also raised Catholic and also sometimes feel some sort of guilt/shame for my ways. That being said, I have been moving away from that by looking at things like this:
1) Hell is for bad people with cruel hearts. Watching porn doesn't make you bad or cruel; it just makes you a normal guy in 2014.
2) If watching porn does make us bad, we'd have to be pretty low on God's list of bad people. When you consider all of the murderers, thieves, rapists, child molesters, racists and crooked authority figures out there, porn watchers seem pretty decent by comparison. After all, all we are doing is enjoying the human sexuality that we naturally have.
3) The Catholic religion, in my experience, doesn't seem to approve of anything remotely resembling fun. When I was a kid, the Catholic church wasn't fond of Pokemon, and instead we were told to watch Veggie Tales and play some knockoff Christian card game. Now as adults, we are told that most of the entertainment out there is "morally objectionable." God gave us brains. We can decide for ourselves what is morally right for us.
4) Did God ever tell you not to do it?