Saira,
You are not alone, and much of what you experience is similar to what others who have suffered such abuse have experienced.
Something happened when I was 5 in a preschool bathroom. It was so horrible that we blocked it out of our memory and refused to use the bathroom there even if it meant pooping in our pants. For over 45 years, we felt the shame and feelings that all the bad things that happened to our family and ourself happened because we were created bad, but never really knew why. When we were a teenager, these feelings combined with living with an abusive father (only emotional/psychological and not physically violent that we remember, but we cannot complete be sure we are not blocking out memories of that time as well). We seriously considered killing ourself lots of times during that period.
We were afraid of the dark as well and had nightmares of evil things chasing us and trying to eat us into our 50's when we finally started facing up to things in therapy. In the dreams, we would try to say no, but could only moan. We learned how we survived the traumatic things we lived through when we were 5-6 and also in our teens by hiding parts of ourself away very deeply both to not feel the terrible feelings and to protect those parts of ourself. The little boy stuck at 5 or 6 has the memories of what happened then, but does not want to remember them. Even feeling the emotions without remembering can trigger a sense of panic. He was able to draw some things of what happened, of being touched in places he should not have been and being forced to do things with his mouth, then something violent happening while being told how he would hurt our family if he told anyone. It took months after drawing those pictures for our therapist before we could being to forgive ourself and see how powerless that little boy was.
Then, little things started making sense like how we avoided public restrooms if at all possible for decades. Or why we did everything we could to get out of gym to avoid changing being undressed in front of people. Even things like a visceral disgust at mayonaise, mustard, and other things of similar consistency and texture likely come from associations with what happened. It took many years of being away from our family, loving support from friends, stumbling into a church that focuses on loving instead of judging before we could come out of shell enough to being to heal.
Keeping things secret only feeds the shame. Talk to your therapist about what happened. Draw pictures if you cannot find the words. Remember that you are not alone.