He may have a different notion of “best friend“ than you do, or he’s telling you “best friend“ because it gives him access to your support and he figures you’d say something if you’re unhappy?

It seems like you’re having a few sticking points here — why isn’t your friend responsive to your needs, why is he not acting like you think a best friend would act? — and they are around the expectations you have for friendship and how he doesn’t seem to acknowledge them, much less meet them.

It’s also worth noticing that your reaction to learning that your best friend is building a family with another woman is to begin to build a case for how he’s inconsiderate of your needs for texting you the news when he did. There might be something worth examining in that.