I actually landed an interview (& am currently WL) at a place where I spoke about being queer & my SO in the secondary. I allowed myself to be super open due to that school's public outreach for LGBT peeps and the nature of the question. It even came up during my interviews and it was super relaxed (even though I felt more nervous about it: I'm super brazen on paper apparently
). However, I did not bring it up at most schools (I didn't mention a SO either way actually) because it didn't relate to the questions and it does not particularly pertain to my career goals (which are 30% undecided lol). I think if it is important to you, and/or your goals/motivations in medicine, than bring it up. Tactfully, of course, but do what feels right & portrays you in your best & truest light. I spoke about my passion for women, underserved and minority populations all through my applications (primary & secondaries) so schools knew what they were getting into and that's the lens I assessed them through as well. (I also applied broadly to cast a very wide net with my somewhat specific/niche bait)
That being said, like others have mentioned, if a school is willing to reject you simply for being queer or out then it shows that they aren't a school you would want to attend anyway. However, I am also Black so I tend to think of things in terms of "making it through"; if you attend a school that is less than friendly or supportive of what aspects of who you are (female, URM, queer), then it is ok to just get by. I have personally been more put off by schools that lack diversity (of race/gender/ethnicity/nationality/socioeconomic status in student/faculty/patient population) than anything else, but if those same schools were my only acceptances I would still go there. You are there to get a degree after all. You can build on that later, but sometimes you will be the odd man out in certain environments for a period of time.
Another random tidbit: I tend to think of sharing my queer status or SO info kind of like wearing my natural hair (which I do a lot). It's an extension of myself & reveals a vulnerable part of me, and how people react to that (or lack to their reaction, which is the goal) shows me things about my environment. But I also use it as a statement to change things for people coming after me; people cannot get used to what they never encounter. Sharing that you are LGBT helps others down the line and helps change views, but there is nothing wrong with choosing not to be the trendsetter. You choose your path and you don't always have to be a blazing rainbow to live your truth and help others. (The world needs both the MLK's & Malcolm X's)
NOTE: Sorry if this got rambly and all over the place. I'll come back and edit it later (maybe)