So sorry this happened to you! Remember, their teasing is a cruety and a reflection on them. You did nothing wrong in liking another person. and he was flirting with you. Know in your heart you were being true to yourself. If you react badly when they tease, they will enjoy it and tease more. If his sister says he's out with someone else, you can say, "You are probably right. Thanks for telling me," like she's done you a favor. When someone says, "Haha, it's never going to happen," just smile and say, "You know, I do believe you are right. Thanks for sharing that." Then they might be a bit guilty for rubbing it in, since you were so nice and polite about it. In fact, the more polite you can be, the better. Then switch the subject to them: (everyone likes to talk about themselves) "Who have you been out with lately?" "How are things with you and your boyfriend? Still in love?" Again, be sincere, like you are chatting, and really, really care about them as friends. It will deflect the subject matter from you and make you out to be a nice friend that they won't want to hurt again, maybe. Worth a try.