Help :(

I’ve had some suspicion of my boyfriend messing around with girls on his phone. The other day I got told he is messaging girls, sending them videos, and making it seem like I don’t live here with him! He won’t let me see his phone and I know that’s enough to show there’s something going on. But it’s hard for me to just leave off of hearsay, we have a 1 yr old daughter and are finishing remodeling our house together. What should I do 😢