Dibbydod
Your daughter were just a child when this happened to a much younger brother, surly not a lot could have happened in view of their ages ,perhaps it’s all been blown out of proportion . Maybe you could bring the subject up so that maybe your daughter could apologise to her brother ? Unless what she did were exceptionally bad , I’m sure this could be sorted out without you having to choose between them as it does seem a bit extreme considering how young they both were at the time .
I’m sorry to say but 12 year olds can be as big and strong as adults, certainly in relation to 7 year old children. I once knew a ten year old charged with rape of a younger boy who had not understood what was happening and was understandably traumatised by the experience. So telling children ‘it wasn’t that bad’ because the abuser was another child is only adding further harm. The only person who can define the level of harm is the person who experiences it, just as it is with adults. We wouldn’t dream of saying to a woman who had been assaulted ‘well he only touched you, it wasn’t that bad’.
Experimentation happens between children, of course. But it is not experimentation when there is an imbalance in age, strength, understanding or consent to take part. Then it is abuse.
My heart goes out to you Nonnak, you are in an impossible situation. Please get professional help to try to see your way out of this situation. It is already causing you immense pain, it cannot be brushed under the carpet any longer.