I Think I'd strongly resent being forced to perform.
Two of my cousins, let's call them Dennis and Daniel, play, respectively, the bagpipes and snare drum. And somehow the pipes and drum always come out at family functions. My two aunts, Sherri and Nora, LOVE the pipes and drums. I HATE the pipes and drums. My ex was also a snare drummer and I was constantly subjected to hours of rattatatttatattatatta while he practiced.
If I try to leave the room so I don't have to listen (as much...to not hear the pipes I'd probably have to leave TOWN) my aunt Nora will screech, "WHERE DO YOU THINK YOU'RE GOING? GET BACK HERE AND LISTEN TO DENNIS PLAY THE PIPES!!! I CAN'T BELIEVE HOW RUDE YOU ARE, WALKING OUT LIKE THAT! GET BACK IN HERE AND STAND WITH RESPECT FOR THE PIPER!!!!"
Even if Dennis and Daniel don't want to play, because they're in the same pipe band and go to frequent performances and practise, their instruments are usually in their vehicles, so there's really no escape from Sherri and Nora, who just won't leave it alone til we're all subjected to several tunes' worth of caterwauling. (Sorry to those who do enjoy the pipes, but for me and my damaged ears, it's torture). I've heard Dennis and Daniel try repeatedly to say they do not want to perform, they just want to enjoy dinner with relatives, etc, but the aunts will NOT leave it alone until they give in. I sure hope this isn't the tack your aunt is taking, OP.
I'm a musician myself; I play the guitar. However, as someone above mentioned (sorry, I forget who) I play only for myself. In the year we've lived together, I think Anthony may have heard me play only once or twice. I do not perform for other people. When Sherri and Nora tried to push me into performing for everyone one time (I had my guitar with me as I'd come straight from a lesson to a family bbq) I gave them a polite refusal. When they wouldn't take that, I gave them a flat, un-JADEed "No."
I don't have much in the way of advice, but I definitely feel your pain. It's irritating too that your family won't let you enjoy the whole thing the way you want to.