I told my family after hiding for 30 years. My Mom had caught me when I was young, but she had never told anybody. She died 3 years before I decided to come out to the rest of my family. So yes, I suppose it's possible to keep it a secret for life.
I came out because I felt like I needed to tell my family. I hoped that they would all be accepting but that has not been the case. But the acceptance from those who did accept my crossdressing has been very important to my own self acceptance - does that make any sense?