It is GOOP. The friend she lost was The Material Girl. We haven't seen them together in ages. The upcoming Vanity Fair article apparently holds nothing back. That's what she's afraid of.
I don't think Goop would be described as a ''celeb'', and I'm pretty sure these blinds would define Material Girl as being A+++. Also, their friendship ended in 2009, and one line implied that the singer had taken advice from Goop, but it was Material Girl who introduced her to health freakery in the first place.
The only other singer I can think of as being recently friendly with Goop is Bootylicious, and I'm also sure she'd be defined as more than ''A list singer''.