Knowing absolutely nothing of your situation (e.g., how often you see nephew and why, etc.) I can only say that I would first and foremost protect the 2.5 year old who is being physically abused pure and simple. Just because it's an 11 year-old doing the abusing doesn't make it any less threatening or any less traumatizing to the 2.5 year old than if it were his own father or mother doing it.
I wish I had an idea, but 11 is WAY too old for this anti-social behaviour to be even close to normal.
I wish I had an idea, but 11 is WAY too old for this anti-social behaviour to be even close to normal.

