Hi David
Welcome to the site. Good start. You here now but as you are very well aware of, you have a lot of programming to unwire.
For starters I would recommend that you search your soul and get all the reasons you have for quitting and putting them somewhere where you can see them easily.
Then cut off the internet as much as possible. e.g. Mobile phone with now internet access.
A web filter needs to be installed on your computer.
Then the biggest thing is to start training your mind to not THINK about porn/sex/fantisize and so on.
Thinking about it will only lead to viewing porn.
Absolution has also come a long way and if I were you read some journals of those that are succeeding, like his.
It can be done, but it takes a huge amount of effort, especially if you have gone into extreme stuff.
Your brain needs to reboot

Try and get as much information about this problem as possible.
e.g. go to
www.yourbrainonporn.comRead books on quitting addictions.
Fight like a crazy Tiger man!
You can do it!
Peter