I know that ultimatums are bad for diplomacy, so I assume that they are even worse for what was once a loving, caring, mutually supportive relationship. I know that you are busy, but could you please answer my questions. I am very upset by this. Basically it depends on who you ask. Lastly, of course it is a problem when the person's partner objects to their use of pornography.
Many people use pornography to satisfy their fantasy life.
It might be similar to daydreaming. Both are forms of fantasy where someone can become someone else and perhaps do things they would not in real life. Thus it is fantasy. How directly one addresses their fantasy life can be a point of contention. I think the real issues is that you feel betrayed.