I don't disagree with the discussions about porn, necessarily...but OP wants to know what to do. My own preference is for openness and honesty...but found that some guys not so keen on this! What can she do? Confront him?
Look I know you look at porn, I've seen it on your phone. What else are you worried about OP? Is your question about whether you can accept your husband viewing porn? Or is it about whether he's keeping anything else from you? Or something else?
I agree with a couple of other posters here that porn is in itself not a deal breaker for me, although it might be for others.
I didn't like my ex looking at porn so much because he berated others for it, was very judgmental of others, claimed to be squeaky clean and then sneaked about looking at it himself. But I find it quite refreshing if a guy says something like 'yeah, I was on my own for x years, didn't have a relationship and I used porn' or even a married man 'yeah, I like porn sometimes, you want to see?'.
I do take the issue re the industry and exploitation seriously...and I'm not belittling campaigns against porn, BTW, but saying that there are personal issues here for OP to sort out with her DH, based probably on trust, respect, openness. Once (if) they can address these then maybe can open up a debate about rights and wrongs or porn and possibly ethical porn, if such a thing exists, I'm sure it must.