I am very honest with both my T and pdoc about my suicidal thoughts, ideations, and plans. They know me well, and know when I am in danger. Yes, they have asked me to go into the hospital on numerous occasions, but because I have always cooperated and gone in willingly I have never been involuntarily hospitalized.
Usually, my husband has already been aware that I was not doing well, so when my pdoc has picked up the phone to call (which he always does when it is time to take me to the hospital), it isn't particularly a surprise.
I would honestly advise you to have someone in your personal life, if possible, who you can make aware of how you are doing and that you might need there assistance if things become dangerous for you and you need to go to the hospital. Trust me. You don't want the police, paramedics, and legal system making that decision for you. It is better to be able to call a family member or friend to help you get to the hospital safely and voluntarily. Your T probably can't be that person by the way. I know mine would call the police to check on me. He's a fantastic T, but he won't put himself in the role of rescuer.
I stay that honest with them both about all things. It is difficult and frightening and a leap of faith to be completely honest about so many difficult things, but that honesty has allowed me to trust, has allowed them to really know where I need help, and keep me safe and alive.