Is it bad to wish I'll upon a child

I subbed for a 6th grade class this morning. I'm black and one of the kids called me a monkey. I told him that's not nice. He said "Well I didn't mean it racially." I told him the fact that he said that means he did. He laughed and continued to call me a monkey and call all the other black kids monkeys even though I kept telling him to knock it off. So I wrote him up. All I could think was "He's gonna say that to the wrong person and I hope he gets slapped for it." Is it wrong to think that?