Your husband probably has a lot of shame about his need for porn. That shame normally begins early in a boy's life, when he can get sexually aroused but can't find a heterosexual partner to release his arousal with. Sex shame is normal for both men and women, because shame (guilt, embarrassment, humiliation, etc.) arises whenever one is excited 9whether sexually or not sexually) and one cannot express it excitedly in one's environment. Your husband doesn't want to talk about what to do with YOU because that openness makes him feel shame--so he gets defensively angry to protect his shame. but his sexual energy is getting detoured into porn fantasies and solo sex; and that is a threat to the sexual union between you and him.
In fact sexual orgasm is normally achieved by both sexes thru a combination of physical erogenous activity and mental fantasies--and the mental fantasies may be the same as what is occurring physically, or they may be somewhat different: "Thoughts are free," especially if nobody but you yourself knows what they are; so sexual fantasies to increase arousal DURING partner-sex are quite normal FOR BOTH SEXES. But many people are raised in religious restrictions against seeking sexual images in their minds to get more excited; so they may have problems getting physically excited enough to reach a sexual climax. This barrier to orgasm is especially likely for women, because they are naturally equipped to be slower to arouse and slower to climax as a protection against getting pregnant in the wrong circumstances or with the wrong man.
If a man is willing to change his fantasies he can alter his mental arousal to focus squarely on his wife. Many men do this by buying or appreciating sexy lingerie for their wives. But it's likely that he would need to talk about this issue and get counseling on how to change from a qualified sex therapist. Most men are ashamed to go into therapy of any kind, so they have to overcome their own shame to do that. Moments of shame and helplessness or defeat in his daily life--at work or at home--are also a natural trigger for him to seek out the pornographic excitement online that he then releases thru solo sex. To overcome the shame of speaking to a sex therapist it is essential that the therapist be able to lower his expectations about shame (since shame is central in porn habituation).
Therefore, I can suggest 2 paths to getting into sex counseling for alleviating your porn problem with his porn habit: Either you say that you're frustrated that your sexual relationship with him isn't rewarding enough for you, so you want him to come with you to a sex therapist to search for a way to have better sex together. This would be the better path if you are concerned that you may have issues of your own with sexual satisfaction. And if you could be seeking better sexual experience for yourself instead of just trying to get him to change, you would greatly reduce his shame by taking on some of the courage to seek help with your own sexuality too. (You might still end up working SEPARATELY with the same or two different sex therapists.)
Or the other path is for you to tell him that you would like to be included in his sexual excitement instead of excluded as you are now; so you have found a MALE sex therapist that he could talk to about how to make your sex life better. Don't mention porn in either overture, because you can show him empathy by avoiding words that would naturally trigger his shame. He needs a "shame-free" confidential contact with a male sex therapist (or the same sex therapist that you're consulting for your own issues) if he's going to learn how to open up about his porn-habit.
I hope this helps. Please ask any more questions you want; for I know how fraught with embarrassment this issue is. Your anonymous approach online is one of the best ways to start the work. But it's not going to get emotionally easier until you're involved with a person whose professional demeanor can reassure you that you're in good hands.