Asshole boyfriend or am i over reacting?

So i went to ross with my boyfriend and baby brother, im also 35 weeks pregnant. We get in line and theres this couple in front of us and the lady was wearing mini shorts. I caught my boyfriend checking her out 3 times and when i confronted him he denied it instead of being real with me which bothered me the most. Then he started insulting me when hes the one thats messing up like are you serious??? The worst part is that he expects me to be completely happy with his actions, called me crazy and said i was overreacting. Was i overreacting or was i right to be angered by his messed up actions???

Edit: My boyfriend and I are expecting a little girl and hes said it himself he'd break a guys neck if they stared at her in a harrassing way??