your both wrong.
jean does die, in a lake in fact, but the entity known as phoenix essentially clones her, in order to sustain both their essences. the problem is, phoenix did it so well, that it forgot what it was, and believed it was really jean.
when they managed to "fix" phoenix, and find out what it was all about, it killed a lot of people on earth, and most people in the shii-ar empire. not because it was "evil" but because thats what phoenix was meant for, to be the rebirth of everything.
jean has actually been cloned twice, one was phoenix, and the second was by sinister, who made her do other evil stuff.
both in different timelines though. in one timeline, jean and scott have a daughter. and in the other, they have a son; cable.
really weird stuff, thats only my interperatation of the story though. im sure a comic geek can correct me though.