I'm sure other people here have been through significant traumatic events. Mine include childhood abuse, rape, and bullying.
Have you ever noticed we face two real choices? Hiding our pasts, so people never know who we really are and we then feel disconnected from them, or talking about our pasts factually like other people do, and then risk losing people who can't accept our pasts or occasionally accuse us of blaming them just for being open.
I've done both. I'm currently in an "open" phase, because I'm in Cognitive Behavioral Therapy. It helps me feel more normal to talk about my past like anyone else, but it's also cost me a few people I thought were friends.
As an Advocate I choose to talk about my abuse, hiding it just made me angry. [bristleconeproject.org]
I may understand better than many people, I was raped when I was 9.
If you survived a painful childhood, it is important to do what you have to do to get stronger. As far as telling people - only my opinion, but don't share until a good trust level has been established. If the wrong people find out that you survived incest, beatings, 20 foster homes, etc. - they have a knife to cut you with. I have read articles about child abuse survivors being "outed" - someone finds out, either by getting info out of the child abuse survivor or by snooping, and spreads around the information, nasty gossip and backstabbing. I have heard of abuse survivors getting "outed" and being dumped by friends, ostracized and ridiculed at work, etc. At a couple of jobs I flat out lied when intrusive bosses interrogated me about my family background. I knew that if I refused to answer their invasive questions, or if I gave honest answers, I would be out of a job. Of course I left those toxic jobs. But keep in mind that some people are cruel and they love to throw acid into open wounds. They love to kick a person who is down.
You can't build trust with someone without being open and honest, though.