Mad Dog, I was there very, very recently. To be perfectly honest, the only reason I’m still alive is my atheism - if I’d believed in any sort of “afterlife” I’d be gone. I was quite prepared for any sort of “god” to send me straight to hell, because hell would have been an improvement.
“How” it happens is probably very different from person to person, so I can only try to tell you my experience. I was past “depression” and into “complete and total despair” - what I’ve just learned is called “existential depression”. Combine that with enormous emotional pain and you can find yourself staring that option right in the eye. Willing to do anything to stop the pain.
Of course, what I was looking for was relief from the pain - and if I were dead, I wouldn’t feel anything, including relief. Realizing that at least made me hesitate and wrestle with the idea instead of doing something about it. What really stopped me, though, was that an opportunity to do something appeared, and I did it - I still have to struggle through the consequences of that, but at least it was, in a way, a new beginning.
I think that is the key to getting through those times - do something, take some kind of action, make a change of some kind - it may be something as simple as going for a walk, or something as major (and cathartic) as setting your car on fire (I know someone who did that, and yes, it turned him around.) If you look at the advice already given, you’ll see that it mostly consists of suggestions to do something - for a very good reason: it works, at least temporarily.
I think FisherQueen’s solution is absolutely brilliant, because it contains so many elements of suicide prevention advice. One thing that often helps is to make a “contract” of sorts - FisherQueen has made a contract with herself that she will only commit suicide in this one way, and her requirements for committing the act force her through experiences that will almost certainly change her mind before she goes that far.
If you go into therapy and admit that you are suicidal, often your therapist will ask you to enter into a “contract” with them - that you will not kill yourself without discussing it with them first. If you aren’t in therapy (please, please try it) but you have someone else you have confided in, make your contract with them, and stick to it!
And, before anyone adds me to their list of people to keep a wary eye on, I am on medication and in therapy, so I’ll be okay. I’m not dancing on the edge any longer.