I am so very sorry this has happened to you. This is what happened to me with my XH, except it was online porn and phone sex. There were also memberships in the adult membership communities. This wasn't a crazy one-time drunk cybersex session or a very healthy interest in porn. It was a sexually self-soothing that he was dependent upon.
I was afraid this might be going on with your H because of some other things that have happened, and I'm very sorry that it has turned out to be the case.
I believe that your H has his own private sex life, his own little world. You have never been a part of it. It has nothing to do with you. It is not because of a lack in you, it is not to hurt you. I would bet that he has had problems with using perhaps excessive masturbation and porn to self-soothe since he was a child. He probably hates himself for it.
He will not be honest with you. Cold turkey is not going to last long with a lifelong habit and it will not change the underlying problems. Prepare yourself in case you come to realize that you have barely touched the tip of the iceberg on this problem. Given the minimum length it has gone on and his invitations to women, I would be very skeptical that he has not met some. Local phone sex calls and chatting will not show up on your bills. A Tracphone can be had for cheaped with minutes paid for in cash. He could have a separate credit card with the bill sent elsewhere. He can get a keytracker to figure out your password for the keytracker and then enable and disable your tracking software to convince you that he is innocent. He can get a phone that goes on the internet so that there is no way for you to track his activity. He can switch to strip clubs at lunchtime. He can hide his porn in a $20/month storage unit. There is no end to the possibilities. You cannot effectively police him.
This private guilt ridden sex world that I think is very very likely probably predates any relationship with a woman and has always been a barrier to successful intimacy. Lying and hiding it has become so natural to him that he likely never thinks about it, unless forced to. For instance, when you try to improve your sexual R with him, it makes him look himself in the face and hate what he sees. So, he pays lipservice to you to get away from that vision as quickly as possible.
If you stay in this R, it will be a long term problem that will arise again almost certainly. Also, it will likely arise again in a more extreme form. Getting past it will take years of work. YEARS. Five, ten. He is crippled at the core in terms of his ability to sustain an intimate relationship with a partner. His emotional growth has probably been stunted from the first time he felt guilty for using masturbation to escape his problem.
I know how much you want to believe the best of the situation. But please please please, keep your eyes open and take good care of yourself. This probably reaches back further than you think and extends further in your current life that you will ever know. The future betrayals will hurt even worse until they become life-numbing, which is worse than the pain.
Unless he does something pretty extreme, like decides without any prompting to check into an inpatient program, I hope you will very seriously consider stepping away from the marriage. For your son's sake, you need to treat yourself and him better than staying with someone currently incapable of sustaining a mature committed full relationship.
Anyway, with respect to his list, that is a big step. I thought your point about him putting you into the position of having to speak up when you are uncomfortable was excellent. You are doing much better on that score than I did in my old M. I was also the one left in charge by default. But, I couldn't step up and talk about it (except in the fairly safe context of counseling, and then only in limited ways). I was silenced by my own fears and insecurities. I really admire your strength and the love you have that would allow you to get past that yourself. I'm sure that whether you stick with this M for the long haul or wind up elsewhere, your strength and lovingness will serve you well. And, if you stay, it will be a very long haul with very risky outcomes -- much more than the one month per year of marriage Michelle talks about. That is for marriages in which both partners were reasonably fully present for at least part of the marriage. Your H, I truly believe, has always kept a large portion of himself outside the marriage in his own private sex world. Like recovering alcoholics, neither of you know who he will be and what he will want if he successfully integrated this part of himself into a person who is capable of sustaining true intimacy.
I worked for 6 years after my discovery of XH's actions, and would likely have worked longer. But, he dropped the bomb, thankfully. I can now see how little progress was made in that 6 years and how pointless it was for me. For, XH did not have the capacity to be the partner that I wanted. Rather, I was slotted into the role of asexual roommate and mother.
Unless this is a major major crises that causes him to take extreme action and clear followthrough, I'd expect little more than more of the same from him in the future.
So, again, right now, quit thinking about being a good wife and a good mother. Ask yourself honestly if what you want in a partner and lifemate is even a possibility for your intimacy-crippled H. And, just take extremely good care of yourself. You'll need your reserves x a million. God I wish I could prevent your pain, I know the devestation too well.