Oh Patrish, I am so sorry. There is nothing you can do to prepare for such a thing except buy plenty of tissues and give yourself time to go through them one box at a time.Your friend will continue to live in your heart. Hold her there and cherish her and the time you had together. Cry for her and for yourself but know that she will always be with you and you will always be able to depend on that memory. Cry for your loss. Cry for the world's loss. Cry until the tears will no longer flow and you lie on your bed spent and exhausted. Then get up from your bed, have a cup of tea and hold her close to you and feel her presence within you. Know her love and her gratitude for having you as her friend.
And then comes the hardest part. Then you have to get up from your chair and go on with your life.
All the best love and hope for you and all who knew her.