Here are a few songs all about confessing!
Confession (usually related to confessing your love for someone!)
Hot Potato - Confession
아무리 생각을 하고 또 해도 믿어지 지 않을 만큼 사랑해
Not matter how much I think it over, I can't believe how much I love you.
BTOB - Second Confession
널 위해 방 안에서 틀어박혀 고백 연습
For you, I stay cooped up in my room, practicing my confession
Deli Spice - Confession
A different kind of confession...an apology!