Not a fan of the snitch aspect. There are a lot of people here who have suicidal ideation but have not gotten to a point where they are willing to act on it. But bring suicide up to anyone who doesn't understand the concept and all of a sudden you have people overreacting or telling you that you're begging for attention. And trust me, going to the psych ward will make your suicidal ideation ten times worse. I interact with people working in the field of psychology every day and trust me, it is an extremely underdeveloped branch of science that requires decades until it'll get remotely close to being effective for dealing with cases like this. It's effective in terms of internalizing a lot of things, getting into a routine and being mindful of yourself, but those hardly apply to someone who is thinking about taking their own lives and potentially already has plans for it. The kneejerk reaction to such cases is essentially lock that person up and pour meds down their throat and when our fucked medical infrastructure is no longer able to support it financially, let them out regardless of whether they get better or not.
The only way I'd tell my friends about my suicidal thoughts is if I know that they'll support me. I don't mean encourage me to do it, but that they'll maybe just be by my side. Also, this his word against your word thing is a slippery slope. This isn't a legal battle in court, and that logic often doesn't apply.