Go to Emergency. It's the worst advice in some situations. There are other options. Sometimes staying with a good friend or family member is all that is needed to get through a crisis. Even talking to a therapist or the like in the community can be a better and less traumatic option than at a hospital. The hospital should be the last resort.
Is it a genuine suicidal thought with intent or a brief thought, like one of frustration? - Apparently some mental health clinicians cannot tell the difference.
I rarely get suicidal. The last two times I felt that way was at the ages of 34 and 42. When I was 34 I didn't tell anyone until 1 year later. Why? Fear of hospitalization and misdiagnosis. The most recent time was last fall when I had a lot of stress going on. I was nearly broke and unemployed due to the public health response. I felt trapped and overwhelmed with the unknown. That time I told the therapist, only because I trusted her. We discussed the possibility of hospitalization, but I turned it down. I told her it would bring back memories of what happened. So, instead we meet weekly for a bit. It was all I needed to sort through my thoughts and feel better. Anyway it was more of an adjustment reaction than an episode of MDD, like I had when I was 34.