I'm just not sure.
Three things are necessary for mortal sin: Grievous matter, sufficient reflection, and full consent of the will.
It might be just an occasion of sin for most.
And concrete evidence of really bad taste... that in itself is pretty damnable in my opinion.
FYI: "Sexual addiction" or "porn addiction" - they are just clinical terms guys... not moral categories. Really. We have "free will". The devil didn't "make you do it". I already tried that excuse - doesn't work.