husband is cheating

I was trying to handle some business with bills and I accidentally found emails from a dating app. He has been on there flirting with women for the past two weeks. Tonight he sent a message to a girl saying he'd like the massage she offered him and that they should meet up. He told another woman that he'd like to thank her parents for creating such a beautiful person. Should I just confront him with it? Or should I be more sly about it and act like I don't know for a while and see if it gets worse?  Oh and I'm 7 months pregnant with our first kid btw.