(((Krazibean)))
I am so sorry you are hurting. May I share something with you? I make decorative boxes as a hobby. I turn shoe boxes into sewing boxes and candy boxes into jewelry cases and so on. The work and love is in the transformation of a plain old piece of cardboard or plastic into something beautiful with my "message" in the artwork that goes into the change.
So, although I know you expected something to be in the box, maybe you can look closely at how she decorated it and see if you can find a message in her work. it takes a lot of time, thought and effort to do this kind of work. So maybe you can think of it the way you would a painting that someone did especially for you?
Having said that, I hope you can tell T that you expected something to be in the box and really looked forward to getting your surprises. I like the idea of writing out how you feel about the whole experience and putting it in the box. Then maybe you can read it to her?
I hope you can discuss this with T.
xoxoxox