Idiom of the day - Sold me out

SOLD ME OUT - when you let someone's secret out, it is said you've sold that person out

Eg.: I trusted Melissa about me copying on the exam, but she sold me out to the principal!

Eg.: "If you don't do as I say, I'll tell mom and dad about you partying last night."  "Oh my God! I can't believe you'd sell me out!"

Eg.: Jason told all our upcoming plans to our rival company! He sold us out!

Eg.: The robber who got arrested sold his entire gang out. They'll all soon be behind bars too.