firstly, I'm really sorry for the OP that she is having such a tough time with this issue.
without wishing to hijack her thread, can I sound a note of caution about the term "addicted" to porn. At the moment, there is a lot of talk of porn addiction - and without a shadow of doubt, there are increasing numbers of men who are genuinely addicted. But I think it is important to look at what addiction really means. By my understanding, it means an activity which someone simply cannot do without, that they systematically return to on a daily, even hourly basis and, above all, that the activity has rendered their life unmanageable - like in the case of lostincornwall where her DH had replaced her with porn.
There are various levels of addiction. Taking the example of coke, someone who does coke recreationally would not generally be classed as an addict. We would probably say they have a habit.
If I may say, I think it might help to make the same distinction with porn because the term porn addict is so loaded, IYSWIM. Of course, none of these semantics take away from the reality of the distress to the OP and I don't mean in any way to do that. But like all habits and addictions, it is the level of the habit or addiction which dictates the necessary treatment and course of action.
I suspect that a lot of men who are bracketed here as having a porn addiction possibly have something more approaching a porn habit. I am not saying that is right either but it is less loaded and, I reckon, easier to confront.
Looking at porn two or three times a week is no more an addiction than having a glass of red two or three times a week (and both, depending on where you stand on the moral scale, can be considered to be vices). Looking at porn every day, often several times a day, and needing to masturbate every time - that is an addiction i.e. the person's life could not get past the need to look at porn at that moment.
I hope that makes sense and, above all, that the OP finds the right solutions for both her and her DP.