Hubby thinks I’m cheating....

My husband constantly accuses me of cheating. Every day, it’s something about how I’m going to my boyfriends house instead of work, or I’m not paying any attention to him because I’m talking to my boyfriend on my phone and he’s constantly going through my phone. I don’t get it. I’m so faithful. I constantly am either at work, or home. I go out every Thursday night to Buffalo Wild Wings with some girls from work and that is it. I don’t know what to do or how to get him to stop saying this. Im 28 weeks pregnant and I don’t need this stress. Any advice?