That kid is either completely heartbroken or a precocious master of the passive-aggressive stab.
Either way, ouch. Poor little dude.
The young lady (and I use the term loosely) in question-- well, I'd like to see her read it. I'd like to think it would be a gut-punch.
I doubt it. It would probably make her feel good. Some neurotypical children are like that-- There's something missing in the brain, they're lacking some essential element of humanity that enables us to execute moral reasoning. (Very tongue-in-cheek stab at recent comments about autism).
Either way-- honey, pick up your breaking heart and teach your kid that some people just aren't worth his friendship. Like that little whelp. Do it now, before he grows up into a big dumb dog of a man who thinks that he can be friends with everyone if he just tries hard enough.
That was my daddy. Most of the time it served him well-- he was a likable guy, missed by all. But it got him kicked and called names and taken advantage of, too; it's also been the cause of no end of trouble for me.
Teach your kid now that there are nasty, predatory s**ts in this world and that this girl is one of them. Teach him to identify those people early. It might hurt, but you are doing him a favor.
I wouldn't do grade school again if you paid me.
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"Alas, our dried voices when we whisper together are quiet and meaningless, as wind in dry grass, or rats' feet over broken glass in our dry cellar." --TS Eliot, "The Hollow Men"