My suggestion - shift your focus from your boyfriend drama to yourself and your baby. He's his own person and he's going to do what he wants to do. Don't worry about who he talks to or whatever. Just don't go there. You're going to be a mother and you have more important things to worry about.
I'm not going to bash your age. You're 19 - you're young, yes. Telling you to grow up is kind of a moot point, imo.
You just need to make sure you're getting your life together. Make sure you have a good job so you can support yourself and your baby. Save up for baby gear. Start planning now, because this is a big job and a very important responsibility.