Discipline and boundaries

I am feeling terrible today following an evening at our friends' house where my 17 year old, very intelligent aspie son ate apple pie when everyone else was eating chili, talked loudly over the top of the conversation without seeming to know how to pick up cues at all, and later referred to their 12 year old daughter as a *** after she hurt his arm in a fight over a slinky toy.  He had earlier spent ages patiently and gently trying to teach her to play chess. 

At home afterwards, he said he was very stressed at the moment and couldn't help how he had behaved.  He has just started college to do A levels and is struggling with the change in working methods so that his self esteem has plummeted as he feels stupid.  Although he has made some friends, he is also subject, as usual, to a lot of teasing and winding up, so no wonder he feels stressed. 

I am wondering today whether I have taught him as much as I should have done about how to behave in social situations, and whether we have given him enough in the way of discipline and boundaries, as we have always tried to support him as a person making his individual way in the world.  My husband says we have done our best and that the problem is that our son cant see there is a problem with his grasp of social situations/rules, the way he behaves.

Is anyone else out there struggling with this dilemma -  support and reassurance/acceptance versus discipline and boundary setting when explanations slide like water off a duck's back?  He is a kind hearted person but doesn't  "get" where other people are coming from.

I would really appreciate any feedback.