In my case, I don't want to tell people in my life about what happened to me. I can't expect them to understand what this is like, and I don't want to have to educate them or manage their reactions. Dealing with my own feelings is enough.
I have told the people I'm closest to that I'm struggling with something. They know that I have depression and anxiety, am having counselling, am finding life difficult and am trying to deal with some serious issues. They just don't know the details. Those are things they can understand and be supportive about, if they're true friends. I feel like I can be myself and talk about how I'm feeling, to the extent that I'm comfortable with. If I'm keeping anything from them, it's my choice and not because of their unwillingness to hear it.
Unfortunately, some people didn't even want to know that much. I had to let them go. That hasn't left me with a large group of friends, but I don't want a large group of "friends" who aren't supportive. Culling friends, especially one group in particular, was hard. I had to mourn the friendship, but I think what I was mourning really was that I'd thought they were better friends than that. I was grieving because the friendship I'd believed in hadn't been there anyway.
There are people who I say much less or nothing to - for example, work colleagues or people in a club I go to. But then I wouldn't talk to them much about my personal life anyway.
I think we have to be realistic about other people's capacity for understanding. I don't know about anyone else, but it's taken a long time for me to get to my own understanding of all this, and I'm the one experiencing it first hand. For me, it's more important that people close to me care about me and want to support me generally. I can be authentic around them without telling them everything.