Take the wind out of your sails

Generated image of a ship with slack sails
The idiom to take the wind out of your sails means to suddenly make someone feel less confident, excited, or proud. It often happens when someone says or does something that weakens your argument or stops your momentum.

The phrase originates from sailing. A sailing ship moves forward when wind fills its sails, but if the wind suddenly stops, the sails go slack and the ship slows down.

Him pointing out my error during the meeting really took the wind out of my sails.