My H is a recovering porn addict. In my case he is trying to quit so some of my advice won't help in your case but I can sympathize with you at any rate.
Porn is an awful degrading addicting monster. Fed by perverts around the world and whores who have lost all honor. It's a strong statement I know in an age that says we should respect others choices - but I call it like it is. It is hard - no impossible to make a man stop viewing that crap if he doesn't want to. It is everywhere.
Just try to Remember it is not about you. It's not about you not filling his needs, it's not about your body or your lack of time, or your nagging or anything else. It is about your H's selfishness, his wish to protect his emotions. His cluelessness about where it will take him and what he could loose. The "ease" of getting the rush of hormones without having to give a darn thing of himself.
Depending on his level of involvement you can talk to him. That is your only tool. Explain how you feel. Tell him you don't want that in your life or that you want to be included - I don't know.
If it is really distressing to you I'd recommend installing a content blocker on the computer. This will only work with his permission unless it is your computer. Content Watch has a good one.
I know that everytime you find him into that crap it will send another dagger into your heart. Until he can face his problem like a man and realize how much he is hurting you you will have to just live for you. And try not to become a co-addict to his behaviors.
DBing is great in this case. Set your boundaries. Tell him what you will and won't allow in your life and then stick to your guns. You have a right to live a life with a dedicated man. Ask him if he is that man.
