I was so shocked and ashamed that I cried when the TA told me! It's really not like him (even the TA said so) I'm hoping I dealt with it in the right way although I fear pregnancy hormones may have got in the way. He is in reception btw.
I asked why he thought I was upset, and he knew and told me. I cried (see those darn hormones) and told him that I didn't like children who hurt other people and that I was very sad because I didnt want to not like him. He cried, I cried more. I asked him what he would feel like if those people had hurt him and if it would be ok, he said no, so I asked what he should do about it. He said he shouldn't hurt people again and should apologise. I asked who he should apologise to and he named the 3 children, then I suggested maybe he needed to apologise to the teachers too as he had made them sad. He agreed. I then told him I loved him very much and didn't like it when he was naughty and he told me he loved me too and didn't like it when I (or his teacher) were sad.
Did I do the right thing (minus the crying obv)? I've also said if it happens again there will be punishments put in place because violence is not ok. It's so out of character though. Am still very 
about it.