I agree, I'm impressed with his choice of words, considering he's eight. As others said he may need a bit of help to make his intentions a bit more clear but still, it's better than the name calling I'd expect from a lot of 8 year olds I've known.
I remember being in sixth grade myself and in one of my classes a boy said something hurtful to a girl, leading our teacher to say "That was ugly." Cue the other kids saying "Ooooh she called you UGLY!" Mrs. C clarified that she was not calling her student ugly, but his choice of words. So I wouldn't be surprised if a younger child like the girl might have heard the words and thought the boy was calling HER ugly.
Come to think of it, I don't often hear people using "ugly" to describe a person's behavior anymore. I used to hear it from my grandmother, but not many others, really.
And well I don't know if it's that the girl hears that at home though it's probably the most likely case. My boys are friends with another kid nearby whose parents swear at each other so much, and not just swear, but scream, that they no longer like to go over to their house.
And I wish I could say I don't swear but that would be a lie. Thankfully my older two don't follow my example. It's kind of ironic really, DH served in the Marines and I have the dirtier mouth?
He never swears at all unless he is really, really upset or repeating a joke where no other word makes sense in context.