Sorry to hear you have to go through this. What I did was approach my manager about coming out and that I did not want anyone to know yet and that I had an appointment with HR. In my initial meeting I indicated my timeline and not to do anything public until that date. According to my plans, one week after returning home I went into work and started the process for my new badge and insurance. At this time they said in one week (and I would not be back for another five weeks) my name would be changed and email address. Once back at work the only thing that was not changed was my core email address i.e. gallaghe@somewhere.com but my viewable email address was Karen.payne@somewhere.com. I asked why and they said if you want we can but it will screw up a lot as I am a developer with many ties to various groups. I opted to leave well enough alone and has not been an issue as when someone gets an email from me it says Karen Payne with the underlying gallaghe@somewhere.com while external entities see Karen.payne@somewhere.com.
Caveat, I work for the state of Oregon where they are sensitive to LGBT community and will and do bend over backwards for these types of situations. It could had been very different for me living in another state and for a private company so I lucked out per-say.
