My feeling is that the image he had in his mind, the ideal picture that he created of you and him together, got shattered a bit. The good times he spent with you, the way he has thought about you, the fun that he’s shared with you——tarnished——because of this one shocking incident. Some guys can’t deal with the thought that “their girl” was touched by another guy in an untoward manner. If that’s the case, it’s a sign of immaturity. He needs time to deal with the “reality” of it. My advice is to give him space. Give him time. He probably doesn’t want to admit that it bothers him——that’s why he is so curt with you. Once he realizes he has to deal with this maturely (if he does), he will come around and interact with you again.