Took my 2 children to the park today and there was a family with mum and dad and 3 kids. Everything was fine then all of a sudden the dad was raging and shouting at his 8 year old daughter, mum was not stopping him. He dragged her by her leg along the grass and started to take her trousers down and shouting he was going to smack her. Mum intervened Dad eventually stopped but proceeded to shout at the daughter.. They went home. I feel terrible that I watched everything discretely and did not help her out. What would be the right thing to do in this situation? God knows what happens behind closed doors.