If he's dating your best friend and you want to take him away, then she's not your best friend because that's a really terrible thing to do. Imagine if you were in her place.
If he's only dating her to make you mad, that's not the kind of guy you want to be with anyway. Yes, I know you love him, but think about what he's doing. He won't talk to you or your family, unless he sees you with another guy. It's not that he wants you, it's that he doesn't want someone else to have you. If he wanted to be with you, he would at least try to talk to you. Instead, he's treating you "like crap" as you said.
He just sounds really immature. He didn't even give you the courtesy to tell you why he broke up with you. This is not how a good guy acts. I don't think either one of you are ready for such a serious relationship, especially having a child.
I also don't think your relationship with him was very healthy. You didn't even want to start any activities, like sports or cheerleading, because you thought it would take time away from him. That's not healthy. In a relationship, you both need to have your own interests, friends, and time apart to grow as individuals. And then if it doesn't work out, you have other things in your life outside of the relationship.
Right now, focus on yourself. Start doing the things that you didn't do because you wanted to spend time with him. Go play softball and join the cheerleading squad. Hang out with your friends (maybe not the one he's dating, but others). Enjoy being 16.
There is plenty of time for serious relationships and kids. Think about all you would miss if you jumped into that now? You wouldn't be able to be a normal teenager or a normal future college student. There is so much left for you to learn and so much fun left to have. Don't limit your options by having a kid with some guy who is acting like he's 12 and you're a toy he doesn't want to play with anymore, but doesn't want anyone else to have.
You deserve better than him.
