Dear Pretty,
I'm sure there are some advice-givers who would question your boyfriend's morality based on this information. But Issuesgirl does not judge! I think a lot of women out there can relate to your situation… I took a quick poll of men I know, and it turns out that most of them also periodically look at porn, and often it's on the internet. Most of these guys are in perfectly happy relationships and are not any pervier than the average Joe. Although my poll was not exactly a scientific study, I think we can assume your boyfriend's behavior is fairly normal. (This is assuming his use of the internet is occasional and is not venturing into addiction territory.)
Keep in mind that, generally speaking (though not always, of course), a man will have a much bigger appetite for sex than a woman. According to a real scientific study, guys are typically thinking about sex almost 250% more often than women are! Ask your boyfriend how many times a day he's thinking about having sex. If he's a young person like you, I bet it's a hell of a lot – and way more than you'd want to be doing it. So, keep in mind that the endless world of debauchery on the web may be doing you a bit of a favor.
I also suggest you have an open conversation with your man about the porn. Try not to make it about your insecurities, but instead, find out what he likes about watching the stuff. The idea here is to demystify the porn and help you feel less threatened by it. Talking about it might lead to new ideas for the two of you in the bedroom. You might even consider watching something together.
Above all, keep this in mind: the sexiest quality in a woman is confidence! If you are feeling self-conscious, do the best you can to fake your sexy confidence in the bedroom. Wear something that makes you feel beautiful, and think about the things that you like about how you look. Once you have pushed through your anxiety, you will earn that confidence for yourself, and you'll never feel threatened by some two-dimensional plastic porno chick again.
Hope this helps!
Humbly yours,
Issuesgirl