Was sexually abused as child (in 4th grade) and nothing was ever done although my teacher at school found out and told parents

As a child we often went over to my fathers sisters house (my aunt) and her husband would make excuses to go "build a birdhouse" in the garage where it was private. We went there alot and it slowly got worse until the point were his privates were taken out and I was forced to do things. He threatend me and welfare of my parents should I say anything about what I was forced to do. My 4th grade teacher overheard me talking with a classmate about how scared I was and took the matter as serious. She did the right thing....my parents were told and we even found out he had once cornered my mother once... I want to know why this never was escelated and CPS, police, courts, etc. did not get involved. All I remember is it being "covered up and not discussed" and us no longer going over there. I had always intended to ask my father why he didnt take this all the way but he is now in stage 7 of Alzheimers. My uncle and aunt are now dead and the abusing uncle died not long after the abuse.