'I want you to know that it was I who discovered your secret.'
This meant LV kept his horcrux information to himself and shared nothing with his death eaters,.
Also in the HBP, Dumbledore says
'I understand that LV had told him that the diary would cause the chamber of secrets to reopen, because it was cleverly enchanted'
This also proves that LV did not tell his death eaters about his horcruxes.
'Had Lucious known that he had a fragment of his master's soul in his hands he would undoubedtly have treated it with more reverance.
