Hi Yedid,
It is with great interest and some admiration that I read your blog detailing the ongoing struggle you are having. I wanted to write you because in many ways your struggle parrallels mine. For many many years I had gone thru the same things as you, trying much of the same solutions (although I have to admit that your ruchniyos is on a higher level than mine ever was). You are fighting the good fight and you are getting great advice along the way!
What is specifically admirable about you is that it seems (without being incapacitated by guilt) that you get back up, you come up with solutions or different approaches to make it less likely to reach the stage at which you are in danger and try again. You write about it and, get great advice, and all in all are able to maintain a positive and constructive attitude. This is a huge accomplishment in and of itself.
Because of what I have been through (and am still going through) I would like to make a small suggestion but I want to emphasize that regardless of anything I say...all of this is just a suggestion and you should do whatever works for you.
A little background first:
I'm a family physician who actually spent much of my early practice doing clinical hypnosis. Although I didn't realize it at that time, I now see that some of the principles of hypnosis could have helped me in the struggles that I had in this area throughout much of my life. One of those principles is that when crafting a hypnotic script to help someone one should should never suggest "a negative" because your subconscious mind will always see it as "a positive". The classic example is if I tell you:
Whatever you do don't think of pink elephants.
You will engage in the struggle to not think of pink elephants and you will end up then thinking of pink elephants!
When we try to fight our lust, I think it works the same way. The more you get down in the dirt and struggle with it the more it struggles with you and the more you think about it. Gradually this wears you down (with me, I would often not sleep the whole night engaged in this useless struggle) and then you give in.
One trick that I am finding is beginning to work with me is to use that mental energy that one would normally use to fight the lust in a different way.
Focus on who you are. You are a child of G-d, infinitely precious to him. This is regardless of what you do or what you don't do. As a Jew, you are a prince, a priest, a member of the holiest nation on earth. When it comes to your interaction with the lower parts of existence, you belong on a throne and you have every right and a God-given r'shus to look upon the "shmutz" with disdain and contempt. These activities are actually below you. When tempted, It might help to actually visualize the throne, imagine yourself in priestly garments looking at the computer, visualize yourself looking down; ask yourself what is befitting for someone of your stature.
Of course, I realize that it's important to be humble; but I don't think that that is inconsistent with an acknowledgment of who you are and what you were created for.
Try to put yourself above it. It's not for you. You are made for higher and better things. Remember that you are basically where your mind is at.
That's all I wanted to say. If it works for you great; if not, just keep on trucking. Regardless, I really admire you.