Sorry to hear about your sis. Pray to Jehovah about this. He will comfort you and lead the way. You should let your sister know how you feel. Try to see if she is repentant and help her understand the value of her relationship with Jehovah. Visiting this forum will not help you. Jehovah knows better that anyone what can make us happy. Listen to him by reading his Word. Find comfort in his words. Talk to an elder and express to him your feelings. This will help you.
Sincerely,
A friend.