I feel bad for not wanting to go but it’s uncomfortable what should I do?

My cousin will be having a bbq with her boyfriend. They started dating a few months ago and they’re doing the bbq so their families can meet . It’s her boyfriends parents and siblings. Also her parents and brother plus my grandma. My cousin invited me although I’m like the only cousin she invited and honestly it’s uncomfortable and I did tell her I wouldn’t go because I’m embarrassed. It’s a honor that she sees me as her close Family member being close cousins . Honestly I did tell her I wouldn’t go . I know she’ll be mad . But I was being honest. I don’t want to ruin my relationship with her because of that . But lately we haven’t been close . Once you date someone everything changes.