I've not yet "conquered" my porn addiction, but I've realized it may have its roots in repressed anger and unable to deal with anger in a healthy way. So I echo the answer of the other comments that mention emotional displacement as the cause. I think the first step is to realize that you're addicted because subconsciously your mind is looking for relief from some difficult feeling you're unable to confront. This makes it useless to try quit by using "will power". Instead I would look for a good therapist who can help with behavioural addictions and with help and hard work you might be able to overcome it. I'm speaking only from personal experience and of course some of these things may not apply to you. But I hope it helps. Good luck my friend.
If you wish to understand more about emotional displacement, depression and addiction, I found two books particularly enlightening on the subject. One is "The body keeps the score" by Bessel Van Der kolk. The other is "In the realm of hungry ghosts" by Gabor Mate. Highly recommend both. The first is particularly great imo.