Suicide resulting from a sudden snapping ... not in my experience. Suicide is usually a thought each of us has had wandering around our brain for some time.
My experience as a suicide attempt survivor, and now a suicide prevention advocate / trainer, suggests that for most people, suicide is the final step in a progression of thought. And suicide is not the result of wanting to die. Suicide will appear to be the only solution, the only mechanism available to end the emotional pain one is struggling to cope with.
It is the pain we wish to end, not our life.
Until / unless we engage our capacity of neural plasticity, the same thought trains keep their patterns aligned with what Ms. Depression needs.