Maybe try explaining that "it won't always feel like this."
Because fundamentally, some of this is asynchrony. Other kids will eventually catch up to notions of fair play and rules of conduct. Grown-ups don't act like that, (mostly-- er, and in front of others, I mean... Hmmm) after all.
As our children get older, they find that different aspects of their agemates 'fit' better-- and some fit worse, at least temporarily.
That's just part and parcel of what it means to be asynchronous, unfortunately.
Does your child have any chance to spend time with true peers? If not, I'd explore some ways to make that happen at least occasionally. That way he knows that he isn't a 'freak' or an anomoly, just different than most people he knows who are his age.
