The other day I was so tempted to tell someone I was gay but then I stopped and it sucks because the person I was going to tell is a guy I like and I’m 95% sure he fills the same but that 5% isn’t what stopped me, and its not fear of not being excepted because I live in California there is a strong gay presence, but it’s the fear of being the gay guy because I’ve been around when the gay guy is the target for office jokes and I don’t want something I do in my personal time to change the person I’ve worked hard to become, and I don’t see why we have to gay first then a person second.
You have the advantage of already being known at work, right? I think they will see your coming out as courageous and probably be more cautious about the "gay guy jokes".
I know what you feel - but I think most of my friends I have told just accept it as another part of me. If I acted very gay (whatever that's supposed to mean!) around them and kept on about it, then I would be seen as the gay guy, but I try not to, so I don't think it influences their opinion of me. I think it's fine telling people you know, it's everyone else I'm nervous about (I don't want to be introduced as the 'gay guy' or have that as part of a first impression. If you tell your closest friends, then of course this won't happen!
Other people can't change who you are... only you can do that. You can't control, ever, how people see you. You can try to influence it but you can never ever control it. And does this guy work where you work? If so, then if he feels similarly to you, one would hope he would respect that what you told him was told in confidence. If he doesn't, then why on Earth would you become known as "the gay guy" at work? Do you think if you tell someone you're gay, or a bunch of someones, everyone will somehow know AND think differently of you? And on top of that, everyone is always "the <blank> guy" at work, whatever "blank" happens to be. As I said, you can't change that beyond a certain point, so why worry about it?