i cant function because my(22M) girl(22F) going away soon. how do i process this?

My girl got selected as a cabin crew, i am so happy. it was her childhood dream and it's coming true. she is gonna be starting her training from January for three months, and then she is gonna be moving away. we have been together for over a year, and i have completed my college. during the last few months i have only been around her. i only go out when i see her and my life has become only her. idk what i am gonna do once she leaves. the thought of her moving out is eating me up. we got this news 4 days ago and i have lost my appetite ever since thinking about it that she will move away soon. i cry like shit. i am really happy for her but at the same time i feel bad that she is moving away. i am realizing how much i am attached to her and it's physically taking a toll on me by even the thought of her moving away from me. i was never like this, i didn't even think i was like this or this would ever happen to me. i dont know when did i become like this. why cant i be happy within myself. i was never the type of person to extract my happiness from others. i dont like how i am thinking and functioning right now. i am sending texts to people which are supposed to be sent to different people. idk what to do in my life, i have just completed college and working on a research paper right now.

nothing exciting happening in my life.