You were one of the people he saved and took under his wings as a part of the Kujo family even before he became the head of the family and he deeply cares for you. Back then he found you in miserable state, you were under shock because of what happened to you, and didn't remember the incident. Recently, you've been seeing many flashback nightmares, and he was concerned, when you told him he realised he should finally tell you

"You have the right to know. It’s my responsibility to tell you"