Growing up, I had many wonderful Christmases. Unfortunately, the one I remember the most is when my father ruined Christmas by getting drunk and mean. All the glorious anticipation, preparation, money spent, cooking and baking was for naught that year. Daddy ruined Christmas.
It was a horrible holiday, absolutely traumatic. I was in 5th grade. I have long since forgiven him, but unfortunately it isn't the sort of thing one forgets. Human beings being what they are, trauma sticks.
So, if you ruined your children or grandchildren's Christmas this year, please get help. You can't change what happened, or wipe it from their memories. However, you still have time to redeem yourself by getting help with whatever your problem is. Make it your problem to resolve, not their problem to endure.