My boyfriend admits I'm not the prettiest girl to him?

Maybe I'm just being selfish here but it really drained my confidence when he said that. I know obviously that I'm not the prettiest girl in the world and he's definately seen better, but its natural to want to be seen as 'perfect' in your significant other's eyes, right? We're in a long distance relationship but obviously we talk a lot and he's seen how I look in several pictures. I told him that I know he could date someone much prettier than me, hoping that he'd say something along the lines of "you're pretty, I want to be with you" or something, but he said "nah, you're ok. I am fine with you, even if you aren't the prettiest." It was..very sadenning. Maybe I'm being selfish. Am I? Should I let him know how I feel or just over look it? I'm very low in self-confidence and this just made things a lot worse, especially because I know a lot of way prettier girls than me live closer to him and he'd be much better off with one of them.