Hello lovely, I'm sorry about what happened to you, but the good news is that it is possible to move on, which sounds like something you really want to do.
First of all, these flashbacks, nighmares and general anxiety all are symptoms of Post Traumatic Stress Disorder (or PTSD), it's quite common among people in similar positions to you. I had it, I'm sure many other's on this website have to, so you're not alone it that, and it's certainly nothing to be ashamed of.
I strongly suggest that you see a doctor, they can officially diagnose you can get proper treatment (like medication and regular therapy).
Also, I'm going to agree with other people and suggest that you tell a family member or a close friend that you trust (especially if you want your uncle to pay for what he did.... I know this may not be the case, but sometimes it is... it's just a suggestion).
Things that I found helpful for dealing with PTSD symptoms mainly revolve around distracting yourself, learn an instrument, read a book, go for a run... just anything to get your mind off it (as long as it's safe). I found when flashbacks are happening, stomping your feet sometimes helps also yelling STOP can sometimes be something.
Also, it's okay to just sit down and just be; cry, write about it in a diary, paint to express yourself, scream, punch a pillow. Just be emotional, just make sure that it doesn't take over.
I have a lot of other things I can share if you're interested, don't hesitate to contact me ok?
You're not alone, and you can and will survive this. I have total faith that you will.
Take care
xx