I think all of us, from time to time, have negative thoughts. That little voice will tell us that we're fat, ugly, stupid, boring, lazy, nobody likes us........etc, on and on. I see them as fleeting moments of self-doubt, a brief drop in our self-confiedence.
But when those voices start talking to you about "wanting to die," it's time to take action.
I suggest you see your doctor for a complete physical work-up and get a referral to a psychiatrist to determine what's going on. Once you have a diagnosis in hand, you can get into therapy and begin the work to move past this.
Please know that you are not alone. There are thosands of people who have been where you are, but with the right help, they aren't there any more. And neither will you!
Peace
Greenlydia