I started the process of letting my managers at work know, but right now I've only told the HR department. And I'm not comfortable to go further.
I've told a few close friends and my boyfriend. My parents and family don't know, and I'll leave it that way. I don't live with them, so my mood swings aren't obvious to them.
It is hard to keep this secret, as you really need the support. PC has helped me get that support, even though it is not personal. You need someone in real life too.