1st January is rather arbitrary for a beginning, isn’t it? It has no solar/seasonal significance and doesn’t even fit with any ancient religious stories.
As far as I can tell, there’s no reason other than Julius Caesar decreed 1st January to be the start of the year on the introduction of his calendar (until c. 45BC the year started in March) and this was retained on the introduction of the Gregorian calendar in 1582.
So, thanks to Julius and Pope Gregory XIII, that makes 31st December an ending.
But an ending of what?
Life and all its idiosyncrasies continues: it will be as good, bad and indifferent in 2019 as it was in 2018.