Ignore them where and when you can. He is your boyfriend and cares deeply for you. What does it say about his siblings who talk like this? It says something about them (and their character) and not you. I'm sorry you were hurt by this situation. Imagine how you would act were the roles reversed? I can tell you wouldn't be part of that because you are a good person. They aren't worth your time and are also no indicator of your self worth. Please be civil to them but don't let them rattle you. Hugs coming your way.