I'm in the US too and I've never heard of anyone getting arrested because they told their T of drug use unless like has been said, if kids were in danger. My boyfriend works in the mental health field and I've heard lots of stories, and no one got arrested because they told their T stuff.

Sounds like you're on the right road to recovery. And being honest about everything is huge. I'd say just start off telling your T that you're afraid, and that you don't want to get in trouble, but you really want to mend your ways and you really need to talk about this stuff.

Good luck, and let us know how it goes.