Here's how to ask for help. You go to the nearest ER and tell the person doing triage, "I can't think of anything else but injuring or killing myself. I really, really want to hurt myself. Please, I need help."

I don't mean to sound simplistic in this. I realize it's extremely hard to do. But it's a start. You could even write it down in a note and hand it to the triage person if you are afraid you won't be able to speak the words out loud.