I had a similar experience, step father not uncle. It was minor sexual abuse - but still not right. I was told that I had made it up to cause trouble (I was 13 and it was Xmas day - drink involved of course) and it has never been dealt with.
I often wondered if I had made it up.
My own daughter came to me a few years ago and said she didn't like the way my step dad touched and looked at her.
Then I really knew I hadn't made it up.
But I have never, ever known how to deal with it. It would break up what small family and 'support' me and my daughter have, but sometimes I have wanted to scream "how is this ok???"
I put a lot of my problems with alcohol down to this incident.
Well done for confronting your parents...it takes guts.