Boyfriend watching porn

Ok. So I've always been the girl to say "it's just porn who cares if he's watching", however it's never been me. I just came home from working all night and my boyfriend has porn up on his iPad. It kinda hit me pretty hard. It's a strange feeling. It made me feel less sexy and less confident. I know that's really stupid but that's the reaction I had. It's not cheating and I don't care if he masturbates but I don't know looking at other girls to do it ... ?? Am I not enough for him? I'm so confused. I don't know if I should be upset or hurt (I feel like I shouldn't) but I am. I'm very ... Shocked. Help? Am I overreacting ?