I do too. Some days more than others, its quite unpredictable. Sometimes its just passing thoughts like geis said, other times I mean it and imagine myself (from a 3rd person view) going through with it. Which as strange as it sounds, offers me some relief. When I told my therapist about this, he said "It could be a metaphor for your mind wanting your situation to change or for your mental torment to end, but not actually by death." Whether that's the case, I don't know, but since hearing that the thoughts trouble me less.