Would it help you in any way to open it with your therapist? It just seems like such a very personal thing to me. I think you have a right to your privacy, even in therapy. Sometimes people feel like sharing an emotional experience with their therapists would ease the potential pain, but it doesn't sound to be your case. It's your moment and your grieving - please don't let anyone take that away from you. It's your right to decide when and how to open your package. I hope there's something good and helpful in there!