I told my family...but they knew.
I can't think of a single family occasion over 10 years where I did not end up passed out or sick everywhere.
You really don't owe anyone an explanation - honestly
No thanks works for me in almost every case.
The only exception is the already drunk and insistent ex drinking buddy. I don't mind telling them I'm an alcoholic. It makes the room go quiet
I should add I spent my first Xmas at home,. alone. It was great. I did what I wanted
D