To reinforce what I am saying above about the importance of the 12-Steps, and also to address (2) your concern that installing a filter can't really help you now, I want to remind you what Rabbi Twerski wrote to you once (since you shared this with me):
Dear Ilan,
The campaign by some haredi leaders to eliminate the internet, even if desirable, is not realistic. While anyone with a bit of know-how can work around a filter, it can nevertheless be of help to a person who is sincere in escaping from this quicksand.
Chazal say, "Tzoras rabbim chatzi nechama." I don't know if it applies to this. Yours was the fourth contact of its kind this week. Internet addiction has become epidemic among the frum men AND women! If you have a fax machine, I can send you copies of letters just like yours.
You are right. Promises don't help and nedarim don't help. Psychiatry and psychology are not of much help. It is very much an addiction over which self-controls don't work.
For alcohol and drug addiction, there are support groups of Alcoholics Anonymous and Narcotics Anonymous. For sexual addiction there is Sexaholics Anonymous.
A frum person will say, "No way I can expose my problem by going to a meeting." I understand. There is a very fine, very frum young man who is in recovery from this problem. He'll be glad to talk with you. He does not need to know your name. The most effective help can come from someone who has overcome this problem. I'll e-mail you his number. You can call him and you will remain anonymous.
Twerski
So Ilan, we see from Rabbi Twerski's reply to you above, that although installing a filter can be of help in keeping it out of immediate reach, it is not meant to be an adequate solution on its own. We also see from his reply that "self-controls" don't work in cases of addiction, and your best bet is a 12-Step group.
So even if you are not ready to join an SA group in your area, join Duvid Chaim's daily group by phone! (See info at the bottom).