I don't know if the rules are the same no matter which state you're in, but no one can technically hospitalize you for SI.

When I first started with current T she used to threaten that. I've been in "the system" long enough to know she can't hospitalize me for SI. When I told her I knew, she was kinda upset...lol.

You can be hospitalized if you are at risk of taking your own life whether it's from severe SI or SUI.

How to bring it up? There's several ways. You can bring up the topic in a general manner. You can say "I have a friend who cuts..." As someone else mentioned, you can bring it up by discussing when you first started. You can also preface it saying you have something to tell her but you have fears and concerns. You can write it and have her read it. It's just however you feel comfortable.

I told my T from day one that I have SI'ed since I was 13 (am now 32). She knows I'm completely honest with her about it, and that I won't hide it from her. She checks in with me every week about my SI. I also cut and I also pick my skin (more an OCD type thing) and I scrub my skin. So she asks about those things and my SUI thoughts. She also sometimes asks about how much I'm smoking. She asks so she can guage where I'm at emotionally.

Many people SI and so many Ts have experience with it. You could even ask your T how much experience she has with treating someone who SI's. And remember, you don't have to tell her everything at once. And you shouldn't be expected to quit instantly. Hopefully what happens is your T starts helping you with coping skill so your equipped to quit when ready.

I see you found the SI forums here. Check out this link for coping skills posted here on PC:
http://forums.psychcentral.com/self-...-yourself.html