First, I want to commend you for being so open, this is great.
So, you know quite a bit about SA, which is fantastic, and you admit to white knuckling it. So you know what you NEED to do, it's just a matter of how to do it?
First, do you WANT to? Like deep down, do you truly want to stop your behavior? If the answer is yes, then that's a great thing.
My husband was VERY emotionally detached. He's got a lot of FOO issues. MC was a disaster at first due to his lies, his emotional avoidance, and his inability to communicate. He would get very resentful, he would shut down, or he would self depreciate. Sometimes it was manipulation of me, other times, not.
We worked hard at communication with our MC.
We both had to learn to not let things escalate beyond a certain point. If one of us was overwhelmed, we needed to say so, and the other needed to accept that. Shelve the discussion after we took a breather and respect it.
I learned to not be accusatory with my questioning. I learned to really control my tone of voice, breathe through the painful stuff. I would write my questions down, so that I could keep control. I would write his answers down so I could remember them and ask for clarification if I needed to.
We would limit the Q&A sessions, shorter at first, then longer when we were able to emotionally handle it better.
If I started to see him shut down, I tried (not always successful, lol) to stop for the time being.
I asked him to understand that I needed the details and why and ultimately it was to help me heal.
There were times that were absolutely brutal. I won't lie and say that there weren't times that we didn't lose it. That he didn't spend a night out on the couch, and well I set some of his clothes on fire in the driveway the morning after DDay2. So I'm by no means perfect. But we just kept pushing through.
My husband still has a difficult time "feeling" his emotions because he shut them off for so long and compartmentalized. It's hard for him to feel the depth of his actions, he said that to me the other day in fact. But he realizes the good it brings too.
One thing about the compulsive masturbation and sexualizing women. It's a cycle. You know masturbation leads to fantasizing, which leads to the need for your drug, which leads to masturbations, which leads to...and so on. Have you thought about stopping? My husband used to masturbate 3-4 times a day, home, work, in his car, whatever. He no longer does this because it causes the compulsive needs. Mutual masturbation? Sure. Solo? No. This was something he decided to do and I fully support it.
As for visualizing other women? He has to shut it down immediately. If he see's someone that he might begin to visualize, he turns away, and starts to think of something safe. Our kids, a special memory, etc. A friend of ours starts reciting scripture verses. Hell you can recite the dictionary, it doesn't matter, it just gives you a distraction until the moment passes.
Also what helped him was going on an anti-depressant due to a post DDay diagnosed personality disorder (mood disorder/cyclothymia, narcissistic personality disorder and OCD). He's on Effexor and wellbutrin. It has really helped with his insatiable urges a lot. He really is happier not thinking about sex literally every minute of every day.