Hey! One quick correction - I’m currently a therapy student. You are correct that if a therapist thinks you are in imminent danger of suicide, you can be detained for a period of time for your own safety. But we are taught only to do that if the danger is imminent. If you are just depressed and occasionally have suicidal ideation, but likely will not act on it immediately, a good therapist would not have you detained. That would be counterproductive.

Definitely just be super blunt and honest with your therapist. They are trained to handle things appropriately. You might hear about shitty therapists occasionally, but most of us are really well trained and really want the best for people.