talebearer

kielikello An indiscreet person who spreads gossip.
1820, w:Sir Walter Scott|Sir Walter Scott, The Abbot, ch. 4:

"To speak the truth when my lady commands me," answered the prudential major-domo, "is in some measure my duty, Mistress Lilias; always providing for and excepting those cases in which it cannot be spoken without breeding mischief and inconvenience to myself or my fellow-servants; for the tongue of a tale-bearer breaketh bones as well as Jeddart-staff."

There is always some thoughtless talebearer ready to gather up the arrows of gossip and thrust them into the quivering heart of the victim.