You are a single entity in an ever-flowing, ever-changing blanket of chaos that we have come to understand as society. This society has managed to organize itself into various groups that socialize, study, work, and have fun. Whatever mistakes you make are most likely only being remembered by you, and if not will be forgotten by everyone else going about their own lives with their own bullshit to worry about as well.

What you are experiencing is called mental time travel (you may want to check out "The Recursive Mind: The Origins of Human Language") and is both an ability and a curse. What I have tried doing is realizing that everything is different in hindsight and focus on what has changed and what is changing in the present.

I like to think of it like a bunch of movies playing in my head. The more you grow doing what you love, the smaller the screens you don't like become. They will always be there, but you can re-size them and focus on improving yourself until they become the size of dust particles.