Whether to open up to colleagues, depends on what are these colleagues. The reaction may be different. Imagine a conversation between the women at work. One: "I went there with my man...". Another: "And mine invited me to the theater ..." Then a third one enters the conversation: "And I am with my girl..." What then? Sometimes the conversation closes down. And sometimes it goes on if there is someone who is willing to support: "Oh, how did you meet? Do you live together?" It's easier when the team has just been formed and the rules are still established in this team. It is significantly more difficult when all norms and rules are defined long time ago, and the team is practically not updated.
If you are already working with these people, you probably have some idea of their attitude to the LGBT agenda. Try to remember how they reacted, for example, to Conchita Wurst's victory at Eurovision or to other news related to LGBT subject. These reactions are very indicative, and the observation is absolutely safe.
If the interest is strong and you feel that fear is retreating, try to develop some of the subjects emerged at work or initiate the subject yourself. The year 2018, for example, is rich in films that are screened and relate to homosexuality: "Colette", "The Favorite", "Bohemian Rhapsody". In 2019 such films will be no less.
Also listen to how your colleagues say, react and respond in conversations about their disobedient children who do not want to be "like everyone else" or even deny "traditional family and marriage." This can also be very informative.
If it turns out that the reaction is distinctly negative, it is worth weighing: are you ready to hide your orientation and worry that everyone will know sooner or later? If not, are you ready to work in an environment that does not accept a significant part of your life, and perhaps regularly listen to sexist and homophobic jokes from your colleagues? I think this is not the best place for finding inner harmony and accepting yourself. Of course, there are risks and advantages in any decision. Try listing and matching them all. Follow what will be more weighty, arm with possible external support and bear in mind the importance of self-support.
In Russia there are definitely teams in which the attitude to the issues of gender identity and sexual orientation is absolutely normal. There are employers whose internal ethical codes include a clause about mutual respect of sexual orientation and the right to privacy, whatever it may be. There are businesses established by LGBT people where the atmosphere is friendly, where sexual orientation and gender identity are of no importance. But it is important to understand that there are few such organizations. For example, if you work in civil service or with children this cuts off any possibility of openness.
In the context of this subject I would like to pay a special attention to transgender people. If sexuality is a part of life that is somehow hidden, then gender identity is who you are. Hiding it from yourself and from others is much more difficult. At the same time any manifestation of gender identity is not at all the same as sexuality. For example, I am an engineer in a big design bureau. I am a man per my passport, but I feel like I am a woman. And then one day I come to work with makeup, in a dress and heels. The acuteness of the problem will be felt immediately! In the best case they will not recognize me and will not let me through the checkpoint, in the worst case - it will be difficult to return at all to this work.
In case of transgenderness the question of whether or not to talk about yourself is often not put. If a person changes documents, brings a new passport to the HR Department, you can only imagine the range of reactions from employees. Or, for example, I have documents for Maria, and I come to obtain employment and look like a man. I am refused immediately. In the labor sphere, the level of discrimination against transgender people is incredibly high.
At the same time it is important to say that there are cases of passing a commission establishing "sexual reorientation" when the transperson does not loose his work. Of course, these are more exceptions, but still there are the people who have overcome the system.