If the person is a total stranger and doesn't know you personally, I doubt there could be anything she could know about you that could ruin your life. All they can do is speculate, and those aren't facts. It's happened to me as well, and I usually tactfully try to remind those ppl that they do not know me or anything about me. When I'm more agitated than is good for me, I simply deactivate my account for a time and go back when my peace has returned. That being said, I suffer from anxiety as well, so I try to be aware of what is a real threat and what is only a perceived threat on my part, because knowing the difference is key for my well being when agitated or feeling overly ill at ease. Best wishes to you!