I'm sorry that happened to you. I can't remember anything similar happening to me but I can understand that it makes you feel awful. We can't know for sure what was going on with them and whether you were the reason why they laughed but surely it is not worth being upset about people like that. I hope you can move on and leave this bitter experience behind, because if they laugh at other people they are the ones who have a problem. If it happens again, I would try to irritate them by directly asking what was so funny and even laughing with them. I hope you feel better today.