Going to Fourth of July BBQ with my boyfriends friends that I dislike 🙄

I need some advice. I’m going to a bbq with my boyfriends friends this weekend. I’m not really fond of his friends. I overheard them talking shit about me saying I’m having sex with some other guy to afford buying gifts for my boyfriend... like wtf? They’re in their late 30’s and I’m 22. So when I’m around them I don’t really talk much. I just feel shy and I keep thinking that they think of me as like some whore which I’m not. I barely know them. I never gave them a reason to think this.. I’m nothing but nice to them. I feel awkward and unwanted when I’m around them and it gets the best of me I get anxiety and I just wanna go home. My boyfriend knows about this and he tells me I don’t have to see them but these people are his family pretty much. I want to make him happy. Is there any advice you can give me on how to act or stop thinking too much? It’s like I can’t even enjoy myself😔 Even if I want to talk to them I don’t know what to say or how to start a conversation... they’re older than me and I don’t feel like I can relate to them. I’m tired of feeling like this every time I’m around them.