I did the same thing last summer and it tore me apart...I was struggling so bad the day before I left that I ended up finding a new T in my new city before I even left the old one. I felt really bad that I was already trying to move on from old T but that's honestly what I needed to survive the transition.

My old T thankfully offered to do a few phone sessions once I moved which also helped the transition.

I totally know how terrible it hurts to know you're going have to say goodbye, I dreaded it for a whole year before I graduated and it took me a long time to get comfortable again once I moved. However, it did happen and my new T has been great. She is actually helping me with attachment stuff and family stuff that my first T didn't.

Just do what you have to do to keep moving forward and talk about it with your T as much as you need to!