You're going to have to inundate her with facts. Just start sending link after link to scientific studies showing that masks aren't effective, the rising rates of pneumonia marked as covid the flat death toll across the board the survival rates vs other common things, the question of where and how the covid virus isolation happened(it didn't, they haven't, it may not even exist), and then ask how can we make a vaccine against an unisolated virus. Flood her with knowledge. She will either change or leave you.