To vent your spleen verb phrase
to release your anger
When things doesn't work out, he vents his spleen on his children.
The director vent his spleen over his employee's ignorance of the law.
You can't vent your spleen to me because it's not my fault.
Express one's feelings of anger very strongly in spoken words
To look or glare very angrily at someone
A woman who has been rejected in love is the one who has the most anger.
To be put in a bad mood
The word "your" should be replaced by other possessive adjectives according to its subjects
The idiom stems from the "spleen", an organ in the body near the stomach. It was believed in European medicine until 19th century from medieval times that the emotion of anger was caused by the spleen which was source of humours. Therefore, anger could be expelled by venting the spleen.
Used to allude that the last force, problem or burden which is seemingly minor and small causes a person, system or organisation to collapse or fail
Her husband's violent act last night was the straw that broke the donkey's back and she left him