Wow, it sounds to me like these people aren't very good friends to have! As for your family, I'm suprised that they've crossed such a line.
If I were you, I would stop talking about the name. Ignore your friends/family when they try to send you messages, and change the subject when they bring it up in person. When someone asks you what you've chosen - say you don't know yet.
Really, the name is a personal decision. Anyone else's opinion doesn't mean squat, so you shouldn't give them the benefit of knowing that it affects you. When the baby is born, name it what you want. People won't have a choice but to stop harassing you about it by then because what's done is done.