If he would not have hidden it, I wouldn't be so upset. I feel like he cheated on me cause he tried to keep it secret.
...hon, he hid it from you because no matter what way you slice it, he probably knew that no matter how it was presented, he was going to receive some type of negative reaction from you - so he obviously just decided to head it off at the pass, and try to eliminate any issue before it started.
For you to say that him watching porn makes
YOU feel like he cheated on you (when he actually didn't, and even if he attempted to stick his wiener in the disk drive of the computer or the VHS tape slot, at least he's not sticking it in somebody else's slot...), indicates that the only issue at hand here...is you.
You say that if he just would have told you, you'd have watched it with him.
Sure, maybe you would have 'just watched it with him,' but then you'd have started questioning his motives, like "do you think she's hotter than me? are you watching this porn because I'm not satisfying you enough? why do we need porn, don't *I* turn you on enough as it is? Are you cheating on me?!?!??!"
Men are sexual, visual creatures. Women are too, but men much more so.
There is nothing wrong with masturbation. There's nothing wrong with watching a little porn while masturbating.
There's also nothing wrong with wanting a little "me time" and having a good ol' fap/porn sesh with yourself.
It does NOT indicate that he doesn't find you attractive, or that you're not satisfying him, or that he's cheating on you, or anything else for that matter. Hell, for me, the more sex I have, the more I find myself masturbating (and masturbating always ensues some serious porn watching, yum yum) because I keep thinking about all the hot sex I've been having and it makes me frisky

Look at it like men do, on the simple surface: I like to masturbate. I like porn. I'm gonna watch a porn and masturbate. END. OF. STORY.