I am not sure I understand.... I mean... doesn't nearly every single person pretend to be 'normal' in public?
We have many, many alters but still have 'friends' in the workplace and in different areas of our lives. Only our DID friend knows we have DID. We share very little personal information with others but different parts of us still enjoy the company of different people.
If you don't want to be friends with others on social media etc you can just say something along the lines of you like to keep your online presence private.

You know there isn't any one standard of a 'normal' person. You're a person. You don't need to be 'normal'. Nobody does. You are a human being and that is enough!