Bella was worried that her powers were so dangerous that it would hurt her parents. She didn't even think about herself, just her parents.
It was true that some kids when they first awakened their powers would panic a bit as something about them had suddenly changed in a way that they did not understand.
Most of them accepted it as easily as breathing, but some of them, especially when their powers weren't so straightforward, they worried perhaps understandably.
Stanley frowned a bit after hearing what the girl had said.
'The cow, that was her doing?' he thought. He remembered the cow that had appeared as if it wasn't eating well or was sick. If the feeling he got just before was her taking away what she called 'life', then it was definitely her owers.
If her powers truly worked by just being around people, then it was really dangerous.
"Even now, I'm taking away your life," she said as fear filled her voice.