OK, I was going to try to write about the emails without including them, but I'm struggling with summarizing, so here they are (anonymized):
Thursday evening:
Hi Dr. [T],

Two things from today that are gnawing at me. First, you said how [Ex-T] gave me 8-year-old information about your son that might not be accurate anymore. Implying that maybe he's not on the spectrum. Which bothered me, because if that in fact is the case, then I feel like you've been dishonest with me. You didn't challenge its veracity when I shared what she'd said before, so I assumed it was true and have been going forward with that info in the back of my mind. Like feeling, without needing to explicitly talk about it, that you understand certain experiences and emotions I've had on a particular level. Which made feel safer discussing certain things. And now I feel like you're trying to deny that's the case? I do understand and respect your desire for privacy, for not giving all the details. But if you're now suggesting it's completely different, that bothers me.

Second, it felt like you were implying that discussing the therapeutic relationship would likely lead to conflict. I want to feel like anything I bring up with you will be OK, that you'll accept it not talking about threats). I want the relationship to feel safe in that way. I know you say that we'll get through whatever conflicts come up, but I want to think that such conflicts might not even *need* to come up, that we could discuss the therapeutic relationship without it becoming this big thing. I want you to be able to accept and contain whatever I say. Yes, I know that may not be realistic for outside relationships, but...I'm also paying you. So this isn't the same as an outside relationship, it's a professional one. I'm essentially paying you to deal with my feelings, and to generally keep yours out of it. Isn't that basically what the therapeutic relationship is about, what makes it unique?

Addendum sent at 2 a.m.
I want to make it clear that I'm really struggling with this. It's the stuff in the first half of the email that's particularly affecting me. (Though I suppose it all ultimately ties into the therapeutic relationship in general.)

T's response at 8:45 next morning (yes, he charged me for this)--a few things cut for space/relevance:
[LT],

I'm sorry that you're struggling with questions about my son, and you are correct about my desire for privacy. I'm not happy with [ex-T's] choice to disclose personal information about my family to a client...

It seems you've developed a narrative about my son from whatever you heard from [ex-T], and from things I have said about Autism. Based on your email I'm thinking that you've interpreted my knowledge on the subject as evidence towards this narrative. I'm sorry that you've felt deceived by my failure to correct your beliefs; however I was not aware that you had such a robust narrative. Your observation yesterday was, as far as I can remember, the first time you've made that narrative so explicit. I chose to say what I did because I wanted to be clear that your narrative was not necessarily true - whatever [ex-T] heard had to be at least 8 years old... and a lot can change over the course of so much time when you're talking about the differences between a 4- and 11-year-old. I have not shared anything more about my son, deliberately wanting to protect not just my privacy but his privacy as well.

I'm aware that you will probably be dissatisfied that I am not going to share anything more about my son's situation. I am also aware that this is a profound difference from Dr. [Ex-MC]. Hopefully we can talk about what that means to you, and how to best cope with the ambiguity. Your curiosity is completely understandable and I'm quite sure I'd have an interest were our positions reversed. We can talk about how important or necessary it might be that a therapist have actual, personal experience with an issue in order to understand or empathize with a client, as well as how important that had been to you in this specific instance. I would like to hear more about how you are reacting to all of this and what impact it is having on you, but I think that's best shared in person....

You also raised the issue of conflict being likely in the discussion of the therapeutic relationship. At our session I was trying to emphasize that it's not conflict - it's intensity and emotionality. Discussing the issues that arise between two people directly is, more so that other things that can be discussed, likely to be intense and emotional. Conflict can arise because of that, but it's not necessarily going to. I think that discussing the therapeutic relationship is a big thing for you, in addition to the content naturally having intense and emotional impact. You make an interesting statement when you say "I want you to be able to accept and contain whatever I say." This reminds me of other conversations we've had, where I've stated my position that there are things you can say that I may not accept. I'm not sure what you mean by 'contain'. If you mean that I will do my part to have a civil, caring, appropriate, and hopefully therapeutically healing conversation with you than yes - you are 100% correct that you should expect that from me and any therapist. If you mean that I should have no reaction or feelings of my own, than I disagree with the statement.

There is a lot to talk about from your email. If you want to address these issues ASAP I could see you at 10:30am today...