I also zeroed in on the use of the word "training" regarding your fiancee's sexual desires.
There may be an undercurrent of dominance/submission in the relationship here. Many people enjoy controlling their partner's sexual fulfillment, which is fine as long as both parties are complicit. Mybe take a little time to think about the power and control aspects of pornography and of your relationship to see how big of a component it is. If it's a big one, you can satisfy that urge in a way that might be more fun for your partner, assuming she likes it too.
If you decide to give up porn (and I think it's a good idea considering your self-proclaimed addiction) then you need to seal yourself away from it.
When you are on a diet, you don't buy a cake and leave it on the kitchen table - or if you do, you shouldn't be surprised when you get hungry and eat it. No, to succeed at your diet you fill your house with healthy food and stay away from the temptation of junk food. When you are addicted to drugs, the first thing you have to do is get away from your using friends, your seller, and all your paraphrenalia, or else you will have too much temptation and give in.
Rather than rely entirely on your own willpower here and setting yourself up for failure, put controls into place that will make it harder to get the porn. Consider cancelling your home internet access. I know, it seems like going without oxygen, but you can use the internet at work for email and other important stuff and just watch TV or play games at home. You will not only be safer from porn but you will find yourself with many more hours in the day
If you can't bear to be without internet access, then install parental controls on your computer and give your fiancee the passwords. Let her support you here. You've mentioned you like the subterfuge involved in "hacking" your porn so this may not help much, as you may enjoy trying to hack your control software, but it could be worth a try. Anything you can do to help yourself is worth it.
You could also set up two user accounts o your computer - one with internet, and one without. The one without internet is yours, the other your finacee's. When you want to use the internet, have her log in as herself and let you use her account for a while. Since it's her account, you will be under supervision and not free to indulge yourself.
Whatever method you choose, make sure you know that it is your choice to do this, and do not fall into the trap of blaming your loved ones for trying to help you. Don't yell at her if she tries to remind you that you shouldn't be downloading that video of triple penetration - she's HELPING.
Finally, if it turns out that you don't REALLY want to give it up. then find yourself a girl who doesn't want sex. Many, many men bemoan having married a women who will never have sex with them - find one of those girls and enjoy being non-sexual romantic partners. But don't torture your poor fiancee by dangling a promise to quit in front of her eyes if you don't really mean it.