I brought this up with T again. I finally mentioned how I am always afraid that people (including him) will discover that I am nothing, that if the layers of performance and dissembling are removed, there is nothing there. That I have no identity.
At which point T mentioned a number of things he knows I enjoy doing, and other things he knows about me, my opinions and fears and so on, and asked me who likes those things, and has those feelings. It was quite a revelation - maybe my identity is also to do with what I like and dislike and think, and not only how other people perceive me.
This became even more powerful because the previous evening, my closest friend had said "you can dislike yourself all you want, but you can't decide what I think about you" - which is sort of the same thing from the other side. I don't know if this makes sense to anybody else, but for me, things really fell into place. T seemed so happy that I'd made this leap, and that felt good, too.
It looks so obvious written down here, but it was a major thing for me. I've been mulling it over since Thursday, and I'm still feeling good about it.