She didn't even tell Yu Jin about it in the decade plus they were together - theoretically it's easier to tell a woman especially a close confidant but she couldn't open up about it. It's understandable she couldn't tell him, especially since being near him would raise the trauma. And trauma takes you back to the person you were when it happened - when she was lacking the maturity and restraint she later had. The people most to blame are the Uncle who abused her and he shitty father.