well, ok. so w and i managed to avoid the topic of "this thing we do" for another two weeks, and didn't get around to telling the couples' therapist about it until yesterday. and we didn't really start talking about that until the last fifteen or twenty minutes of the session, so we really only just started the whole process of discussing it.
one tip:

if you can talk about it without giggling nervously and looking really uncomfortable, that might make the therapist better able to understand that you aren't ashamed of what you do, and aren't asking for her to help you to overcome this dynamic, and heal from your need for it.
even so, i think it went well. we'll see next week. the part i'm a little concerned about is making sure we're able to convey that the ambivalence we have is NOT about whether or not to do it, but about *how* we do it... and also, about the fact that we're kind of braced for people disapproving.
i mentioned how it's kind of similar to coming out as a lesbian, in that even if you're pretty sure you are one, and you're comfortable knowing that for yourself, and all of that, you're still gonna be nervous the first few times (or first thousand times) you tell someone else.
the difference for me is, i've had far more examples in my life of people being out about their sexuality than of people being out about DD. and far more negative examples in the world of people who do DD who are NOT people i'd want to be associated with (no offense to those who really agree with the whole "surrendered wife" thing).
AND, in terms of my chosen community, there's a lot of really negative, judgmental attitudes, and narrowness about "what it means to be a feminist." , and that's part of where i'm coming from.
so, yeah, hopefully we'll see in a week or so how our couples' therapist handles us "coming out" on this topic.