Undoubtedly what your uncle did is a crime that deserves punishment in this world and torment in the Hereafter. Many people’s religious conscience has been weakened by what they see and read, which provokes their desire, so they fulfil their desires in ways that Allaah has forbidden. One of the most abhorrent and evil examples of that is incest between a man and his mahrams (female relatives to whom marriage is forbidden), which is deserving of a severe punishment in the Hereafter.
Your mistake was not telling anyone in your family so that they could put a stop to what this uncle was doing. But because that is in the past and has now ended, and you hated the situation from the outset, there is no sin on you now.
You have to try to forget the evil thing that he did, and learn a lesson from it for the future, for yourself and your children. We advise you to pray to Allaah and ask Him to relieve you of your worry and take away your distress. Some du’aa’s that have been narrated in the Sunnah are as follows:
(a) It was narrated that Anas ibn Maalik said: The Prophet (peace and blessings of Allaah be upon him) used to say:
“Allaahumma inni a’oodhu bika min al-hamm wa’l-hazn wa’l-‘ajz wa’l-kasal wa’l-bukhl wa’l-jubn wa dala’ al-dayn wa ghalbat al-rijaal (O Allaah, I seek refuge with You from distress, grief, incapacity, laziness, miserliness, cowardice, the burden of debt and from being overpowered by men).”
Narrated by al-Bukhaari, 6008.
Ibn Hajar said:
The interpretation of these things is: “distress” means bad things that the mind imagines are happening at present; “grief” for what has happened in the past; “incapacity” is the opposite of ability; “laziness” is the opposite of being energetic; “miserliness” is the opposite of generosity; “cowardice” is the opposite of courage.
(b) It was narrated that ‘Abd-Allaah ibn Mas’ood said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “There is no-one who is afflicted by distress and grief, and says: ‘Allaahumma inni ‘abduka ibn ‘abdika ibn amatija naasyati bi yadika, maada fiyya hukmuka, ‘adlun fiyya qadaa’uka. As’aluka bi kulli ismin huwa laka sammayta bihi nafsaka aw anzaltahu fi kitaabika aw ‘allamtahu ahadan min khalqika aw ista’tharta bihi fi ‘ilm il-ghayb ‘indaka an taj’al al-Qur’aana rabee’ qalbi wa noor sadri wa jalaa’ huzni wa dhihaab hammi (O Allaah, I am Your slave, son of Your slave, son of Your maidservant; my forelock is in Your hand, Your command over me is forever executed and Your decree over me is just. I ask You by every name belonging to You which You have named Yourself with, or revealed in Your Book, or You taught to any of Your creation, or You have preserved in the knowledge of the Unseen with You, that You make the Qur’aan the life of my heart and the light of my breast, and a departure for my sorrow and a release for my anxiety),’ but Allaah will take away his distress and grief, and replace it with joy.” He was asked: “O Messenger of Allaah, should we learn this?” He said: “Of course; everyone who hears it should learn it.”
Narrated by Ahmad, 3704; classed as saheeh by Shaykh al-Albaani in al-Silsilah al-Saheehah, 199.
So do not give in to the pain of the past and forget yourself. You have to keep yourself busy with acts of obedience to Allaah, such as memorizing Qur’aan, reading books of knowledge and the biographies of the righteous salaf, and look for good friends.
We ask Allaah to bless you with that and more.
And Allaah is the Source of strength.