It was as though, so long as the deceit ran along quiet and monotonous, all of us let ourselves be deceived, abetting it unawares or maybe through cowardice, since all people are cowards and naturally prefer any kind of treachery because it has a bland outside.
There are no more uses of "abet" in the book.
Show samples from other sources
The man who could not be discourteous to a ground-squirrel had sat in the courthouse abetting the cause of grubby-minded little men.
Harper Lee -- Go Set a Watchman
Not telling her is tantamount to aiding and abetting the enemy.