You are so very brave to come forward and to "tell" someone of what has happened to you, I want to say how desperately sorry I am that you have been violated, that someone has exposed you to behavior that is not wanted and not acceptable and mostly not appropriate.
Can I say from a mum's point of view you are very right, you mum will be probably very angry, but not at you kiwi//pigeon, at your Great Uncle. I think that it is important for you to tell her and try not to run the scenarios through your head as to how she will react, I know this is hard but we really never know, but it is so very important that you do tell her. There are a few ways to do that, you can write her a note, you can even show her this post if you find talking to hard, but I as a mother would want to know, to be able to support my child and to the together discuss what needs to happen next.
I feel like some professional support would be very good too so that you can get some help to manage the thoughts and to be able to talk and to have some support to help you through this process. The longer that this sits with you unattended the potential it has to turn into something quite nasty and you do not deserve this in the first place let alone it manifesting inside you and getting worse and impacting more of your precious life that it already has.
If your mother does not believe you or you find her not supportive, you keep going, to another person whom you trust, to another adult, you keep speaking until you find your person who will help you through this. Regardless of what happens to the Great Uncle, you need to get some help and you need to be able to live a happy life without this pain.
I am so proud you reached out to us today and I hope that you feel support and comfort here, we are here with you to sit with you, to listen and to help you work though this journey to getting back to being a healthy and happy person.
Kids Helpline also have a webchat service and I understand that it is quite busy at this time so there may be a small wait time, but please persist as they are son wonderful, I will put the link here:
To answer your question......NO...NO..NO...this is not your fault, this is not your fault, this is not your fault.
We are here for you.