GuiltyInky,
I'm worried about you. At 4+ years out, your train of thought reminds me of someone just a few months out. While I'm concerned about your marriage, I am more concerned about you personally. The traits that are destroying your marriage are the same ones that will continue to destroy your life whether or not your marriage survives or not.
I know this might be weird advice and others may disagree with me, however, I am going to suggest that you give up trying to save your marriage, at least for now. Not that you shouldn't try, or that you should leave your wife... that's not what I'm saying. Rather, I'm saying that you are simply not (IMO) capable of working on the marriage right now. How are you going to fix the marriage when you can't even fix yourself just yet?
To me, you scream of someone buried in shame and panic. I know the feeling well, that's been me for a long time, and I'm still working on it.
Here are some things I suggest you discuss with your IC:
1) Why you love/value yourself so little that you don't demand more of/for yourself in your life. A person who loves/values themselves doesn't need someone else to make them feel loved/valuable.
For example, your need to apologize to the AP is not about the AP, it is about you and how you feel about yourself, and the need for the AP to still see you as a "good guy". You are attempting to feel valued through her, not through yourself.
2) Who are you? Discuss who you are and who you want to be. Then take steps to become who you want to be. It HAS to be for YOU, not for anyone else.
Would you like to be a liar? If not, then be an honest person. If you want to be an honest person and still feel the need to lie, then explore that. Why would anyone feel that way?
3) What are you afraid of? What triggers you?
What does it mean to you if you never watch porn again? What does it mean if your marriage fails? How much of what you do to save the marriage is being done "to save the marriage" and not just because it is the right thing to do in the first place? Be honest with yourself on this... If you only stop watching porn because your wife wants you to, and not because it is something you no longer will accept in your life, then you are manipulating your wife and your marriage to your own ends. Or put more simply, you are being dishonest and inauthentic.
Hang in there GuiltyInky. Dropping the ball so far into the game can often make us want to quit and throw in the towel. I am proud of you for reaching out for help, especially knowing that 2x4's would be tossed back in return. All you need to do to succeed is to not give up. At some point, the tumblers will click and things will start to make sense. You will know it in your soul when they do.
Personally, I found that I clung to my own pain and victimhood for a long, long time. My identity as a victim was like a warm blanket. Even though it hurt me, it was the blanket I had always known, and the one I reached for to comfort myself, because feeling like shit was what was "normal" to me.
First, a new "normal" needs to be defined by you. One which you are proud of. One that you want in your life. One that replaces the shitty coping skills that led you to having an affair, lying, sneaking, and so on.
The goal is simple. To live a life that you are proud of, to be someone that you are proud of being, to act in ways that you are proud of acting, to have the integrity to do the right thing when the wrong thing presents itself, and to go to bed each night knowing that you are a good person and that you have done your best in all things. Do these things, be this person, and everything else in your life will fall into place.
For now, go take care of youself.