Thank you everyone for your advice and understanding.
One thing that has become clear to me is that I don't express emotions well. My ability to put on a neutral face has definitely made the situation worse, as it seems no one else realized the depths of my hurt over what was moving forward.
I realize in retrospect I thought that I was *not* hiding pain before, because I could regularly talk calmly about what I was feeling and have the occasional quietly tearful night. To me, this was as close to wearing my heart on my sleeve as I get, but from the outside I looked like someone who was handling everything quite well - having a few bad days here and there but generally coping successfully. But my communication habits were obscuring the intensity, frequency, and depth of my pain. I was hiding it without thinking I was.
It's not enough just to talk about it, I think. I have to figure out how to externalize raw emotion in ways I have practically never done. I've been thinking a lot about how to make friends with emotion, so that my instinctive reaction of shame toward feeling something strongly doesn't cause me to clamp down. I don't have any answers yet, but it is at least useful to be conscious of the problem.
And Juliet and Charlie - they need to listen more openly, not try to hear what they want to hear, which is of course that I'm fine. They need to treat me like I'm trying to do something that's incredibly hard for me. They need to keep in mind that while everything they're doing with each other now is old news to them (they did all this and more weekly during the affair), it's the first time *I've* had to deal with it. They need to remember that even though it seems like they're doing the right thing when they ask me "so, can we do X, now?", it really just puts me on the spot. I feel I can only say yes if I want them to be happy, and no if I want to stand in the way of their happiness. I want them to approach me with more sensitivity than that, knowing that the answer will probably be "yes", because I very much want them to be happy, but that it may also be very hard on me. I look strong, but they need to remember how vulnerable I am.
I think they're willing. They offered to take a 3-week break to give me some time to decompress, starting today. I feel lighter, knowing things aren't going to continue accelerating for now, and I hope to make some progress on my ability to externalize by the time things start up again.
I don't want to become the vocally bitter mono who ruins her partner's every enjoyment of poly by reminding him that she's still hurting. But as you guys have pointed out, if that's where I'm at, it's not much use to suffer quietly until something like last week comes along and blows the lid off. I'm not sure how to find the middle ground, but it's got to be there somewhere.
One step at a time...
And what shoulder, & what art.
Could twist the sinews of thy heart?