in your heart (of hearts)
idiomPart ofheart
in your heart (of hearts) — idiom
1. If you know something in your heart, you have a strong feeling that it is true,
1.idiom
Definition
If you know something in your heart, you have a strong feeling that it is true, even if you don't admit it.
Example
In her heart of hearts, she knew she had made the right decision.
He knew in his heart that he would never see her again.