My boyfriend's brother is just mean to me, how to react?

I have a boyfriend that I love very much. We've been through ups and downs and decided to give each other another chance and stay together. Few days ago my boyfriend's brother and his girlfriend who live abroad came to visit for a week. I have been doing my best to make them feel welcomed in our apartment. We arranged expensive road trips and took them to nice restaurants and sights. However since their first day they've been quite impolite. Anywhere we go, they wont talk to me. If my boyfriend is around then they say something, as soon as he's not they just starring on me. Whenever I ask them something they just won't answer. They have not asked me one single thing since Wed and this whole situation just feels incredibly ridiculous especially because genuinely I've seen them second time in my life and first time for more than 1 hour. I just don't know what to do anymore. My boyfriend says nothing and the only thing I do is pay for loads of things we all do together but feeling horrible. When his brother thought I am not looking he's been making funny faces of me and showing me off.Imagining that once I would have to stick with those people as a family is making me cry. Am I wrong? Am I the one who is annoying? I just feel so sad. Is there something I don't see? Please what is your opinion? I don't really know how to continue with this whole situation. I know they will eventually go back but still I am left dubious if I fit into these people.