Ask yourself, what are you afraid of?
By your expression, this is more than annoying potential encounter, Ms Opalescent.
Perhaps you fear your sister will belittle you? Perhaps you feel your own accomplishments are insignificant, so allow me to list them for you.
Travelled to the Crystal Empire by a Royal request.
Made several new friends.
Learned of a new culture.
Had your first dance with a stallion.
Completed your mission. (forgot what that was)
Returned home with a new best friend.
You have much to tell your sister when and if you chose to meet. You've come a long way sense you last saw her.
Guess there's no more avoiding the inevitable, is there?