This is something that I think I can help you with. Social behaviors need to be taught to children with Autism, they don't seem to come naturally to them. We have been very sucessful with our son in this department. It takes a lot of work, but the results are WONDERFUL!!!!!
So much of language is nonverbal. Being able to read a person's body language is so important to figuring out how to act in a social situation. I really think you can teach this.
How is he reading other's facial expressions?
Unfortunately you can't put links on this site, but if you try to find "facial expressions," many educational sites have drawings and/or real photographs of people's expressions.
Now when I'm upset with him I ask him,"what does my face look like?" and he is getting it.
He notices me all the time now and will say to me "Mommy your'e happy." I JUST LOVE THAT!!!!!
I also use "social stories." Again they can be found on the internet. I am making my own now and have a book of them for school also. I have stories about "why we raise our hand in class." "What is a good friend." "Why are we quite in a resturant."
I watch him constantly with his brother and sister. When he takes something away I ask him "how does that make your brother feel?" When his brother takes something away from him I ask him how does that make YOU feel? I correct him all the time and make him repeat "May I have a turn please?"
It is almost like being a little angel on his shoulder and guiding him socially.
You also have to treat him as if he is typical. Be firm, have expectations of him and if he doesn't do it...... punish him.
Before we go in a store or a resturant I lay down the rules. If he pitches a fit, we take away some perk he has. "If you don't stop it now you will not go in the pool today." I count to 3 and if he doesn't, no pool.
I can honestly say this is working. Maturity does have a big part too. We saw a lot of growth from kindergarten to 1st grade. So hang in there. So many typically kids pitch fits too. Just try to laugh it off. Odds are you will never see any of those people again anyway.

If they are going to judge you as a mother or your sweet son they are not worth it.
Have a great summer. Fall will be here before you know it.