>>87476995she died two times, once in the 80s, at the end of the dark phoenix saga, and the second time, when she was killed at the end of Morrison's run by Xorn-Magneto, like in 2004.
The first time she was meant to be dead forever, but a few years later Busiek, who was a fanboy of 60s xmen and hated having Jean dead, became a Marvel writer, and retconned her death into being the death of a perfect clone with all her memories created by the Phoenix, while the real Jean was in a coccoon in the ocean around Jamaica. The coccoon was found by the Avengers.
She has been death since the end of Morrison's run around 2004. The current Jean is young Jean Gray brought from the past by Beast along with all the original x-men from the 60s.
she became evil in the dark phoenix saga. it isnt clear if becoming evil was unavoidable, or if she became evil only because of being corrupted by the mind manipulation of Mastermind.