vent (one's) spleen
To voice one's anger. Mom's been venting her spleen to me for an hour already. Apparently, Aunt Marie has wronged her yet again.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
vent one's spleen
Fig. to get rid of one's feelings of anger caused by someone or something by attacking someone or something else. Jack vented his spleen at his wife whenever things went badly at work. Peter vented his spleen on his car by kicking it when it broke down.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.