No I don't think it is.
I do think porn use is because we know how problematic it is.
We know that it gives a misogynist and negative view of women.
We know that men who use it a lot, want to try some of the stuff they see in porn on the real women they sleep with in RL, who may not be willing to do that stuff.
We know that men who are regular porn users, often lose interest in real life sex and are often really shit lovers - the OP has indicated that their sex life is not brilliant "nothing to set the world on fire"
We know that the women in the porn industry are overwhelmingly victims of rape and sexual abuse and that 70% who leave the industry, suffer from PTSD, a rate comparable to that of torture victims, fire brigade personnel, army personnel, police officers, etc.
And the OP has made it clear she hates it. And the OP's DH, has made it clear, that he doesn't give a shit if she hates it and he will unilaterally carry on doing something he knows upsets her and if she raises it as an issue it ends in an argument, so it has become an elephant in the room in their relationship.
And having elephants in the room, is a betrayal of a relationship. You can't do that and have a healthy relationship IMO.
I don't approve at all of what the OP is doing. But frankly, I don't think she's doing any more harm to her relationship, than her DH is. They are not communicating and not showing each other respect, as someone pointed out earlier on.
That's a betrayal of their relationship on both sides.