I want to find my long lost daughter and tell her that I'm her dad.
Why would you just show up in your estranged daughter's life like that?
I just want to see her reaction when I appear in front of her.
It is good to tell kids the truth, but there is a time and a place. You should talk with her mother because she might take it badly and be upset.
It's my kid, I can do whatever I want.
You can't just show up unannounced and all of a sudden tell your daughter that you are her father. This will be a great shock all at once for her to find out and it could damage her psychologically.