My labmate, my advisor, and I were talking about Halloween costumes and I said I was going as one-half of Kris Kross (90s rap duo), and I ended up saying that I was dressing up with my boyfriend. He didn't seem particularly fazed by it--I think he's seen me wear a rainbow bracelet so I have a feeling he already knew--but it was still kind of a big deal to tell him. We're in a very open-minded field so I couldn't imagine there being any negative reaction, but still. Especially because he's never been one to take interest in our personal lives. Yay!
Congratulations. It is good that you came out to your graduate advisor. Being a bit more open about yourself, and also for your graduate advisor to get to know you a bit better, can help in your academic relationship with him. Should ever there be a need for you to speak with him about more personal things affecting your academic work, being out to him, could make it easier.