I have this horrid gut feeling that my fella and his baby momma are doing things behind my back and I don’t know how to go about talking to him about it.. anyone give me any tips?

Just little things, like he’ll lie about being with her and their child. They’ll go out shopping as the three of them. The messages back and forth and they got closer again all of a sudden then I find out she’s pregnant again... I just pray it’s not his 😢