In fact she seems to be there just to deny Jacob's idiocy, but it doesn't help. According to one of the books, she got married. No one really cares; after all, she's human (and not Bella). Why could Jacob possibly care about one of his older sisters when he has a baby to take care of? Oh well, at least Meyer didn't have the chance to ruin her, as she wasn't relevant long enough.
Unfortunately, she has since divorced her husband for not supporting her singing career. She has released a song named 'Friday', which was a huge hit on Youtube.