I've lost my grandfather too and we were very close. I understand what you are going through and I'm sorry to hear about your loss. It might help making a certain small table or a wall area a memorial to him to honor him and how much he has meant to you. You can start with placing your favorite photographs of him with other things that represent things he loved to do, and whatever else you feel is appropriate. Some people have incense and or a candle and or flowers or a live plant. The holidays are the worse while you're mourning a loved one. Hang in there and allow yourself to grieve.
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Whatever you think you can do, or dream you can, begin it. Boldness has genius, magic and power in it. ~Goethe
Your Aspie score: 167 of 200
Your neurotypical (non-autistic) score: 35 of 200
You are very likely an Aspie.