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.
It's hard to see our kids hurt. My ds is sensitive, and I worry that this trait is particularly difficult for boys. I think practicing is the only way things have gotten better for him. Practicing with same -age peers and even practicing dealing with my dh's good -natured teasing has helped - slowly. We also use a concoction of empathy, humor, and tough love depending on the issue.
