I think there's two things you should know that might make you feel more comfortable about honestly seeking help.

First, you can say an awful lot to a psychiatrist before they will have you involuntarily held. The idea is that you have to be an imminent danger to yourself or others. "Sometimes I feel like killing myself" is usually fine, "I think I'm going to kill myself tonight" will get the police called for your safety.

Second, I think you're imagining involuntary mental treatment the way it is portrayed in horror movies and not how it works in real life. I sat through an involuntary hold in an ER with a relative of mine, and it was basically like any other hospital visit. They checked her physical health, and then a psychiatrist came by to talk about why she had said the things that got her taken in. She left about 12 hours later with the name of a local therapist and a prescription for antidepressants. Even longer stays are going to be a lot more like a boring hotel than like an insane asylum.