So sorry.... and yes, don't pick up calls from her....
If you DO happen to go to A meeting, and she "happens" to approach you, take a deep breath, look down at your feet, like you are shy and like you have a hard time speaking, (not mad) and say,
"Well, I wasn't going to tell you, but ummmm, one of the biggest reasons I don't make it to so many meetings is, well...... you. I don't like facing you, and the things you say to me are well, actually not very encouraging and I feel so bad afterwards, you know? "
Then just look at her, and walk away.
If she says anything else like "you need it" or "I am your big sister, and I am helping you"..... just reply, "See?" Then shrug your shoulders and walk away.