This is something I have to reflect about, changed a lot for me in recent years.
What part of yourself do you feel like you need to hide?
I currently do not feel like I need to hide anything, but that still doesn't mean I "out" myself for everything. Not yet sure if this is depraving myself in some form, but I consider it a privilege for people to know these details about me, the least they need to do is ask (specifically).
Of course there are some thoughts and opinions I do not share without making sure whoever I share them with is able and willing to understand.
How open are you with people IRL about this side of you?
I have no IRL people being comfortable with all these sides of me, but if someone asks, and asks again (I get them to confirm they're serious about what they just asked) I tell them a lot, only stop if they get really uncomfortable. I consider that affirmation
If you have shared this side of you with others, what was their reaction?
Mostly this:
"TMI!" - "I did not want to hear that!" - "Why did I ask?!", and silently: Not asking me any more questions. I find it funny, but also sad.
Sometimes people are inquisitive about details, which I like even more! Like the other day we were nerding about rubber clothing kinks, only to realize we were talking about totally different forms of rubber! (latex and neoprene). By the time we were done we were alone in the room.
Is there somebody you wish you could share this with, but are hesitant to do so? What is holding you back?
No-one in particular. Always looking for new subjects to torment with details though
Who do you absolutely not want to find out about this side of you? Why?
I used to say "anyone, particularly family and friends", but nowadays I am confident to say that if someone finds out, it's because they asked or inferred based on their own experience. Both I am comfortable with.
What I absolutely hate is when details about my kink are gossiped about with uninitiated people. What I say I say to people, or in communities, with intention - carrying it out is a breach of trust. The reddest of flags for me.