Would you feel attracted to someone who is critical and angry?
It is quite possible that you have some unexpressed anger from before you even met your husband. Only you know though... see how you feel about your father, or other people from your childhood and see if this is maybe a case of transfering your deep burried emotions onto your husband.
To me, it seems that the amount of anger you feel is disproportionate to the "crime" commited. Thinking about leaving someone for looking at girly pictures? hmmm, sounds like bringing a nuclear weapon to a used car dealership.
See, when anger is not proportionate to the problem, then it points to some other cause for anger: a cause which is burried deep down in our subconsciousness because it is usually directed at people we feel we shouldn't get angry at, like our parents for instance. Resolving those issues, which takes some help from outside (a good therapist), I think will make you a whole lot more realistic about other people's mistakes, and even more approachable and able to enjoy life.
BTW, I notice good looking women all the time, and if I like some, I look up their pictures on the net. I just like appreciating their beuty. It is interesting to me. And my wife doesn't mind. She does the same. I don't do it every day, or even every week, but sometimes I do it. We have our favorite actors and so on... my favorite actually died, but I still like the way she looked when she was young and I admire her for it. I also look up pictures of my favorite cars, or even my favorite places to visit. Does that mean that I would like to cheat on my wife? No, I like beauty, whether it shows in female body, child's smile or Ansel Adams landscape. Try to see it that way. Just because someone was nasty to you, doesn't mean that your husband is against you. Seeing what others do as directed against you prevents you from enjoying life to the fullest. Instead of having the sex of your life with your hubby, you are spending time on the internet and in negative thinking. What's the point of that? What can you gain from that?
Also: imagine you take this "all the way". For instance, you get a divorce, get all nasty with him, tell him everything you think about him and so on. Then you're alone. Maybe you even find a new guy. Your kids are growing without a nice family. That stays with them forever ( did you have a whole family, or just one probably angry parent?). That sadness, as you most likely know, is something no kid needs to experience.
Then later you get old. The new husband didn't work out either. Now you're old, alone, and you start doubting whether it was a good idea to leave good husband because he looked at a few pictures on the net (what if he bought sports illustrated, would that be just as bad?). And in being alone, you have all the time in the world to remember your childhood and you remember some stuff that you never saw in that kind of light... someone hurting you emotionally and so on... And you realise that maybe the anger that made you live your life alone was misplaced. It was supposed to be directed at someone else.
Would you be happy finding that out when it's way too late, our would you rather have known that on time?
ps. I too was getting angry at my wife for small things. It was partially heavy metal toxicity that I still have, and also it was unresolved issues with my mother. One very good psychologist once asked me, when I was livid with my wife: - Did you ever feel the same about your mom? And that was the moment that changed my life. And we all live with it - anger that is misplaced. Anger that is directed at a wrong person. But it doesn't have to be that way.