It is indeed a difficult situation. Sounds very similar to a situation i had in highschool. I was so close with this girl jenn and i did not have many friends back then either. We told each other everything and trusted each other and she went off and started talking and hanging out with these girls who made my life crap. I ended the friendship because i felt betrayed as well and i always regreted it. What you could do is just be compeletely honest with her, tell her how you feel. Tell her that you were sorry for what happened in the past and you know she forgives you but it has bothered you. Keep in touch with her through messages, You may be moving to another country, this doesnt mean visitations are not in order. My husband moved from another country to be with me and he still visits all of his old friends. A great way of communicating and staying close is letters. Not emails though they are great as well. But sending letters makes you feel like you are young again writing notes to each other about your life and how things are going and everyone loves recieving letters in the mail its exciting. I hope you all the best