Your dad died a year ago and you are still grieving terribly. I'm so sorry. This is the sign that you need to see a grief therapy counsellor to help you move forward so that you can enjoy your life. Your dad wouldn't want you to suffer like this.
It just happens, comes and goes. Probably will help once the holidays are over. My sis died this year, and I realize how much she meant to me over the holiday. Just hang in there or speak to a therapist or join a group.
One day at a time, sometimes one moment at a time. I still quietly grieve for my mother, but it does get better, I promise. Stay active, lean on loved ones and know that you will get thru this. You are in my prayers. Blessed Be.