I know how Christmas has been crushed for the loved ones and community surrounding those who have died in the recent shootings. I have just read how New Life has canceled their Christmas show, out of respect for the families, and from their own community sorrow.
Brothers and sisters, I know how you feel, and how it is to have a life snatched away from you, even during the time of the greatest expression of joy, such as Christmas. I agree that if your heart is not in it, it is too much to sing joyous songs when tears run down your face and your heart is broken.
I hope this reminder will be of some comfort. A mere three days after Christmas, December 28, we remember The Holy Innocents. These were the innocent babies who were slaughtered by Herod as he heard rumor of the birth of Christ. All children of Bethlehem up to the age of two years old were murdered by Herod's soldiers who hoped that Jesus Christ would be one of them.
So even at the first Christmas there was barely time to rejoice as Joseph protected Jesus and Mary and fled with them at the warning of the angel. An unknown number of babies were murdered and their parents hearts were torn. The Church remembers these holy innocents as the first child martyrs of Christianity and know they have paradise with Christ in God's home.
It has always been a cruel world, but there is no doubt that nihilism and violence have reached unprecedented levels of arbitrariness, cruelty, randomness, senselessness, and as a unique affliction of youth.
So do not feel that you must force joy as your hearts mourn and eventually heal. As I've said, the Holy Family themselves had little to rejoice even in the days following the birth of Jesus, except of course their escape from the murder of their times in human history.
God bless you and provide you with solace and comfort.