Your situation is tough. And I mean REALLY tough. I suggest reassuring her a little, because not only is this move hard on you, its hard on her too. She's probably a bit stressed out, and all she needs is for you to say, "Please, try to stay." or something like that. Tell her that she's an amazing friend and that it wouldn't really be the same without her. All she probably needs is reassuring words and good friends by her side. Hope this helps!
~More Smore~