I'm not sure about my relationship

I'm 28 weeks pregnant. And my boyfriends been wonderful during my pregnancy. But sometimes I just thinks he isn't ready, he wants to go hang out with friends, which some are girls, girls he's hooked up with before. And I didn't bother to get an invite. But he still wants to go. Have a "casual drinking night" with all them and I told him I'm not comfortable with that. And he tells me to get over it. Sometimes I feel like I'm the only one in this relationship that is actually preparing myself for this baby. While he still wants to go and party.