Is there a supplication that can be recited to help overcome the effects of the harassment the questioner experienced in her childhood, knowing that she did not inform her parents about it?

Your uncle's action was an ugly and reprehensible crime, and the mistake was not informing any family member. Since this matter has passed and you detest it, there is no sin upon you. Try to forget what happened and learn from it for the future. Pray to Allah to remove your worry and grief with the prophetic supplications: "O Allah, I seek refuge in You from anxiety and sorrow, and weakness and laziness, and cowardice and miserliness, and the burden of debt and being overcome by men," and "O Allah, I am Your servant, son of Your servant, son of Your female servant. My forelock is in Your hand. Your command over me is everlasting, and Your decree concerning me is just. I ask You by every name belonging to You, which You have named Yourself with, or taught to one of Your creation, or revealed in Your Book, or You have preserved in the knowledge of the unseen with You, that You make the Quran the spring of my heart, the light of my chest, the dispeller of my sadness, and the remover of my anxiety." Do not surrender to the pain, and busy yourself with obedience to Allah, memorizing the Quran, reading books of knowledge and the biographies of the righteous predecessors, and seek out good company.