Wandering eye..

So I've had the same discussion with my boyfriend about him looking at naked women online whether it be porn or videos people send him on social media. To me it is extremely disrespectful to our relationship for him to be constantly looking at other naked women who look NOTHING like me. It makes me feel like he's not attracted to me and it makes me wonder why he's even with me if he needs to look at other women this way. His argument is always "I will never meet these women in my life" but to me that doesn't make it okay. I don't look at other men and have no desire to. I keep finding naked videos and things on his phone and I don't know what to do. It really hurts me when I find these things. Am I over-reacting?