In such a situation, you can go to the wedding, greet her, take a gift and say Salam to the people present, and when the music/dancing starts, quietly leave the hall. She might still get upset, but upsetting her is better than violating Allah’s laws and giving your approval to haram acts through your presence. If she rebuked you, tell her that you broke Allah’s laws and you pushed me to do this, so don’t blame me. I love you as my sister by Allah comes before you.