to confide in someone; to reveal or disclose one's feelings, secrets, or concerns frankly.
友達に悩みを打ち明けた。
I confided my worries to a friend.
彼女はやっと両親に留学のことを打ち明けた。
She finally told her parents about studying abroad.
信頼できる人にだけ打ち明けるほうがいい。
It's better to confide only to someone you trust.
長年の秘密を打ち明けるのは勇気がいる。
It takes courage to reveal a long-kept secret.