We have some good friends who lost a husband/father/grandfather/friend this year. We have prayed for them everyday since and we are praying for them extra much now that Christmas is near. I remember what the first Christmas was like after my mom died. My father, my sister and I (ages 16 and 18 respectively at the time) felt the emptiness and loss probably more at Christmas than at any other point in that first year. And we continued to feel it subsequent Christmases also.
While the loss is felt at all times, at Christmas families have special traditions, special familial "liturgies" that are part of the culture of each particular home and family, and when someone is no longer there to participate in these liturgies, to play their part, we not only miss them as a person but there is a loss to the entire culture and ethos of the family. At times when everyone is gathered together for special family celebrations, the loss is multiplied; everyone's loss is compounded and realized - as though each one is losing this loved one anew - as they come together, for part of that 'together' is missing, missing from each one and missing from the whole.
Desiring God has some very timely thoughts about suffering and loss at Christmas time, and how to minister to those experiencing it here and here.
Also, from the same place, here is some good counsel from Charles Spurgeon on sharing the story of God's grace in your life through Christ at Christmas, here.