I'm going to echo Muz for a minute here and say agian that this being a computer forum might not be the best place to find an answer. However, since you seem to be sincere with trying to address this like a man (which is pretty rare by the way) I'll offer what insight I can, from one adult to another.
I want to start by asking you a question. Why is her looking at porn a bad thing? We seem to have this idea in America that no female looks at porn which is simply not true. Most of my female friends admit to watching it on a semi-regular basis. You said it appalled you so I'm not sure if that's because of this stigma we have against girls watching porn or maybe it's a religious/cultural thing for you.
If it is a religious or cultural thing that goes against your beliefs, what do you want to happen? I see three possible outcomes here:
- You could ask her to stop, which could lead to a little resentment or even watching it behind your back
- Reconise that she does have urges too and move on (which in my opinion is the best of the options)
- Or, if it's a big enough issue, leave her.
Obviously none of those choices are easy but those tend to be how this works out (from personal experiences being on the other end). Again, I think that the best option is number 2. Watching porn is far from cheating on you and is a great way to relieve stress. Who knows, maybe you two could enjoy watching it together.
About the videos, why did you go looking for more things to get angry at? Yes, I would have done the same thing in the heat of the moment but in the end it really does nothing besides make you more upset, and her upset later for looking through her personal files. You neglected to mention how "new" those videos were, or even how long you two have been dating. Maybe they were for an old boyfriend that she never deleted or needed extra cash at some point and got paid for it. From what you've told us, we don't even know that she is still making those videos. I would ask her about them, but be prepared to hear that it was for an ex, or for a job. In this day and age it is very common as people try to make ends meet.
As always, Muz has great input on actually talking to her. Pick the time very carefully and be ready to listen. Most importantly, do NOT be confrontational. Finding that she's been visiting porn sites is one thing because of how it showed itself, but snooping for the files is another. If you go in yelling/angry i can guarantee she will be nothing but defensive and nothing good will happen.
And have the questions Muz asked answered. Also have loose plans on what you will do if you like her answers and don't like them. I say loose because you should always leave room to compromise the outcome.
Good luck.