So I started the session with "so there's something I want to talk about, and there's a first part and a second part, and I know you're going to want to talk about the first part, but I want to get to the second part and then later we can talk about the first part" and he said okay.
And so I told him

I told him that I'd been really angry at myself about this. And then I was angry at him. Probably at least in part because in the mental war between the two opposing sides, he represents the pro-"LabRat not hurting herself" side. And there was a lot of fear and doubt about what will happen if this doesn't work.
I told him that I'd written an "unsent anger letter"/journaled about it. He seemed pleased to hear that.
I told him there were a million levels of catch 22s regarding whether or not to share it, that it was an angry letter and I wasn't sure how well he could compartmentalize, but if he doesn't have superhuman powers of compartmentalization and detachment then it would probably not be a pleasant thing to hear. That I had reservations about sharing it because I wanted to protect him from that instead of trusting him to be responsible for handling his own emotions. But also that, while I wasn't actually feeling the anger at that moment, at the time I'd written it and considered whether or not to share it that I had wanted it to hurt him. And that cruelty was not okay.
I explained that if he said yes to me sharing it I'd feel guilty. I knew he'd feel a professional obligation to make the judgement call he thought was in my best interests, so it wouldn't really be fair to put him in that position. And that if he responded by being hurt then I'd feel guilty and would worry about sharing things in the future. If he wasn't hurt then I'd tell myself he didn't care.
If he said no to reading it then I'd feel like I was being told that I wasn't allowed to be angry or that my feelings don't matter.

At some point towards the beginning of this when I told him I was angry he asked me if I could look at him while we had this conversation. It was different than the way he's asked before. It's usually been when I'm talking about something I'm really ashamed of and it's a kind of coaxing (?) thing, trying to bring me out of my shame a bit. I don't remember exactly how he phrased it this time, but it was more along the lines of him thinking it was important for me to look at him during this conversation and wanting me to try, and actually making it a request. Like he wanted me to actually express my anger. During the entire thing I looked at him like 5% of the time, which is more than usual.

He wanted me to communicate about my anger and stuff and wanted to know. And to tell him when I was angry at him. And I was like "well I just did," but he meant the specifics. Like the letter. And he said "how about you be responsible for your own emotions and feelings, and I'll be responsible for mine" and when I asked what he meant it was basically that I was sharing/owning my feelings and he was responsible for handling his own.

So I did hand it over. He started reading it out loud, which he's never done before with the things I've had him read. I kind of cringed and said I'd really rather not have to hear it again (because I was feeling guilty... I had been angry and these were cruel words and this is very unlike me). He said he'd rather hear me read it, and I shook my head and he continued reading it.
It included things like:
"if a patient gets better you get to congratulate yourself on a job well done and take it as evidence to support the stupid naïve world view that with enough hard work and determination anyone can get better. And if a patient doesn't get better, you get to tell yourself that they just weren't trying hard enough or that they didn't really want it enough."
"and if you have to actually see them get worse you get to terminate whenever you ****ing want to so that you don't have to see it and then you get to tell yourself it was for their own good. Because your intentions were good and that makes everything okay. And then you get to move on and forget about it because you told yourself you were doing the right thing."

He kind of half humorously noted that those words sounded familiar. He'd reassured me over and over that, while he understood his mistake, his intentions were good and that he had thought he was doing the right thing for me. Which I know is true logically, and if I didn't believe that I wouldn't be working with him.

"I bet you wish you hadn't seen me again so you wouldn't have to know how much [you terminating in that way] ****ing hurt. You still don't even know the details. You're welcome for that, by the way. And that's assuming that you actually care."
He asked what I meant about the not knowing all the details part. He we'd talked about it and he had a general idea

The letter went on about how yes it was my choice but if he'd actually cared enough to really think about it, what did he really expect to happen? And that "if I can't do this (I'm sorry, I mean if I don't want this enough or I'm just too weak)" he gets to do the same thing again with a clear conscience.

"Isn't it convenient that you don't have to care about someone if they're not getting better, because clearly they don't care about themselves? I wish my job worked like that, but I don't get to just ignore data if they contradict the thing I want to believe and only care about the data that give me the results I want. And then tell myself I'm a great scientist because my intentions were good and therefore the only reason an experiment didn't give me the results I wanted is because there must have been something wrong with the thing I was using. It just wasn't good enough."

There was a off topic conversation at this point when he said that actually was a kind of research bias and I spent like 30 seconds trying to remember the specific term for that kind of research bias. It sounds trivial, but it was nice to have that kind of break from the things in the letter and it was just the two of us talking as people who both have training in research.

"You're not the one who has to care about what happens if I really do try and it still doesn't work out and then I have to deal with how much I'll ****ing hate myself for allowing myself to try. The idea of how much I'd have to punish myself for this scares me."
"But at least acknowledge that there really is a risk for me.
If a tree falls in a forest but you don't have to be there to hear it, it still matters to the ****ing tree."

He thanked me for sharing that with him, and he sounded genuine.
He said he really does believe I can do this, etc. And that there are people who aren't at a place where they're ready or able to make the choices like this, but that he believes I am.

I told him that it still feels like the wrong thing. That the belief that it is morally wrong for me to want/need other people is not something I can just decide not to believe any more than I could be convinced to not believe that "hurting other people is wrong."
He said I could use his judgment for that when it feels wrong, like think about what he would say. And I pointed out that that would require trusting that his judgement was correct, and the letter made it pretty clear that I was not convinced of that.

We talked about motivation. He asked what had changed that made me throw out my stuff. I told him that I didn't care about myself, but I wanted to care about myself and I know that I'm not just going to wake up one day and magically care about myself, that it will take work and changes in behavior to lead to the changes in thoughts and feelings.
He was glad about all of this. I told him teasingly not to get too smug. He emphasized that he didn't take credit for my choices and that this was me doing the work and acknowledged that he can only imagine how difficult and painful this is and he's not the one going through it.

He said I'd made some assumptions in the letter about how much he does or doesn't care that weren't correct. And basically said he did care.

It's been more than a day now so I'm probably missing pieces of dialogue. But in general the last part was positive and there was a bit of joking/teasing and I left feeling relieved and more committed/motivated. Which is really annoying. I kinda wanted to sulk for a bit. How the hell did it go from me walking in with a letter of cruel and hurtful angry things to ending all positive and motivating?

Oh, and at some point when he was admitting he cared he said something kind of half teasingly about how about how I've been "growing on him" and he thinks he's been "growing on me too." And I know he meant "I've come to care about you," but my brain also helpfully misinterprets that as "I hated you at first but I've learned to tolerate you somewhat."
And ugh, now I have to decide whether to ask for reassurance on that one on Monday.