Boyfriend made a secret Snapchat to talk to girls

My boyfriend left his phone in my car after I dropped him off to work.. as I’m telling myself I trust him he loves me I don’t have anything to worry about, another voice is telling me just look. So I do.. and I found out he made a secret Snapchat and had only added girls to it. He’s had this account over 2 months now .. when he called to find his phone I asked if he had anything he had to tell me that he was hiding and he kept telling me no .. oh ? Nothings wrong? Ok. So I acted like nothing happened.. but he could tell I was mad and he knows that I know. Idk what to feel I’m so hurt. Is breaking up with him over this too much ? I just really feel like I can’t trust him now. How do I know he didn’t hook up with any of them ?

I forgot to mention I’m 25 weeks pregnant with our baby boy 😔