I first wanted to say thank you for posting these articles and questions/answers. They are very encouraging and I am thankful for your commitment to scripture.
I am a baptized Christian man in my mid-20s. My wife (also a baptized Christian) and I have been married for several years now. I did not grow up in a New Testament Christian home. I developed bad pornography and masturbation habits as a young teenager. After starting college, I found my own way to Christ and realized that these lustful habits were sinful and have been battling them ever since. I never committed fornication and never have and never would commit adultery.
Anyway, throughout this battle, the hardest part has been the guilt and feeling that I need to confess to my wife when I have been having a relapse in my lustful behaviors. This helps get the weight off of my chest but causes her quite a bit of pain. What do the Scriptures have to say about these sorts of matters? Must I confess these sins to her or is a confession to God enough considering that I continue to fight this battle?
When a husband tells his wife that he is using pornography, he is simultaneously telling her that she is inadequate to satisfy his sexual needs. This is why it upsets your wife when you tell her you are struggling against pornography.
What you need to do is get help. Find someone you can talk to about your struggles and why they are arising. "Therefore, confess your sins to one another, and pray for one another so that you may be healed. The effective prayer of a righteous man can accomplish much" (James 5:16). This person doesn't have to be your wife. Second, it is time to start doing some radical things to change your habits. Install a monitor on your computer and phone that alerts your trusted friends that you are looking at things you shouldn't be seeing. Examples would be Covenant Eyes and Ever Accountable. You might look into limiting your access to pornography by blocks, such as OpenDNS, putting blocks on when you can use the computer, moving your computer into a public area of the house, changing to a non-smart cellphone, etc.
While your intention is to never commit adultery, the problem with pornography is that it plants the idea of illicit sexual encounters constantly in your mind. Eventually, this repeated exposure is going to wear down your defenses. This is what Paul talked about:
"For this is the will of God, your sanctification; that is, that you abstain from sexual immorality; that each of you know how to possess his own vessel in sanctification and honor, not in lustful passion, like the Gentiles who do not know God; and that no man transgress and defraud his brother in the matter because the Lord is the avenger in all these things, just as we also told you before and solemnly warned you. For God has not called us for the purpose of impurity, but in sanctification" (I Thessalonians 4:3-7).
Paul's argument is that God wants each Christian to be holy and set apart from the world. But that can't happen when a Christian is involved in sexual sins. But to stay out of sexual sins, a Christian has to have control over himself. But you can't remain in control if you keep chasing after lustful things. This is the deception you are telling yourself right now; that you can chase lust and somehow remain in control.