I definitely think Mulder will try to stop her from killing herself. But I don't think she'd ever truly come back from a loss like that, especially since she'd hold herself responsible for his death as long as she lived. I'm not one who ordinarily believes suicide is the only option but in this case, since we know in The X-Files universe there is an afterlife, perhaps she would be better off, though that would leave Mulder to grieve on alone.