This is a truly tough one to call If one is an immediate danger to self or others that initially sounds like a time to tell your therapist or pdoc. Conversely the way some members here describe psych hospitals or psych wards it sounds like a rather difficult decision to tell or not to tell. I can't imagine any place more depression than either place to somebody who is suicidal IMHO the MH system long way to go to reach even minimal decency, effectiveness in care.