I use my wife's first name, but then again, she's involved in my therapy at times, and knows my t (has been to session with me on occasion). Other people just get descriptors because it's easier than saying a name, then having to explain the relationship. Occasionally, I will use names of family members or close friends. I've used first names of other t's.
My t sticks to confidentiality pretty well, so I have no concern about her contacting people without my express permission. There's also nothing "reportable" that I tell her, as I'm not a minor, under guardianship, or fall under any other "mandated reporter" category. The only person she could call anyone on would be me, and that would only be if she believed I wouldn't get myself to safety after a conversation about it...