Oh yeah, I'd totally be bothered by it, but luckily you are due first, so if you have a girl, you use the name that you decided on. I'd consider not talking about names so much anymore, especially if it is making things awkward and she won't talk about it. If it were me, I'd probably say something more to the point though, that I would never do that to her and I'm upset that she's even considering the name that I had chosen. But that's just me- has the potential to cause more drama.
This is why I'm not talking names with anybody. Personally, I don't think a very good friend would do that to me, but I don't want to give anyone ideas either.