Cheating boyfriend

How can someone tell you they are in love with you and had a whole kid with you. He said he had 1 kid. I moved in with him. When I finally went to his phone he had 3 kids. And he’s still flirting with his babymama. Talking about how their sex life was. I'm dying on the inside. I don't know what to do. If he didn’t want to had a relationship with me why did he even bother😭😭😭😭

We are living in the same apartment looking at each other. I can’t afford to move out. I’m really dying on the inside. He keep asking to give him another chance😑 like sir wtf.