I need advice so badly

Hey girls, (and the few guys I see on here...) I've been with my boyfriend for almost 2 years. I love him dearly and he makes me such a better person. He has helped me build my confidence and love myself. the past few months, he's been glued to his phone. I can clearly see he's looking at girls' Instagram profiles that are way prettier than me. It hurts so bad that he can lay next to me like I'm. not here and look at other girls. here's where it gets messy and I start feeling like a horrible person... All I want to do is talk to my ex about it and vent to him. I don't know if it's because I actually miss him, or because I know he's hung up on me and I can easily get his attention. I have never ever ever ever EVER had thoughts about another guy while in a relationship and I feel horrible. what is your opinion on this situation? I know I need to tall to my boyfriend about how I feel but as far as thinking about my ex... is that normal? it's been 5 years since we broke up.