Think my boyfriend thinks his ex is more attractive than me and it bother me even though i know it shouldn't?

Maybe he meant it in a way that most men would be more attracted to her because she looks a lot more 'easy' than you do. I know that's a mean thing to say since I don't know her, but honestly you are a LOT more prettier than her. She does look very fake and kind of stuck up, where you look happy and like someone who is a nice person and fun to be around. Just by my judgment, I don't think he meant it in a way to say he thinks she's prettier than you. He may not realize how he made it sound. I don't know. Just ask him about it casually, he'll give you his answer and it'll be fine. But whatever he says, I think you are way prettier than her. Good luck!