I'm so sorry for your loss. The holidays are especially hard times in this regard. This will be the second Xmas since my dad passed away and I'm thinking of him all the time (he liked Xmas a lot).
Being sober will also be more challenging than normal, probably because it's hard to feel normal while part of your heart is missing. Ultimately I tell myself it's just another day, that I will get through it, and that getting drunk won't bring anyone back or change things for the better. As my dad lay dying in the hospital I bent over him and whispered that I'd make him proud of me. Being sober is part of that.