She's showing you she has value, that she's desired by other guys. She probably saw you flirting with some other girl or thinks or knows that another girl likes you. The thing about being suicidal probably means that she was so hung up on some guy in the past that she felt like she'd die without him, and she never wants to feel so dependent and powerless again, so she avoids that by reassuring herself and showing you that she has options. If you bail or freak out at the first sign of that then you can't handle an attractive woman.