Dear Twilight Sparkle:
Okay, first of all, while it was indeed my idea to send you to Ponyville, it was you who decided to stay in that hellhole. Thus, anything that happens to you in that town is entirely your own fault.
Second, anything Pinkie does to you does not affect me, so I have no reason to worry.
Finally, you are a selfish bitch who treats everypony around you like crap, so you completely deserve anything she does to you.
So in summary, the answer is no. You cannot come back to Canterlot. You still have a lot of lessons to learn in Ponyville.
Your ever-sadistic former teacher, Princess Celestia.
P.S.: Pinkie Pie makes some truly delicious cupcakes! Why not try some?