Thank you all SO much. It means a great deal to me that I'm not alone in this miserable frustration, nor in feeling at a loss as to how to fix it.
I've gotten some phenomenal advice here; I think that a week-long break (NOT a week-long binge, haha!) from counting/monitoring/hand-wringing is what I'll try. A week of following the same dietary guidelines I've been following, but without pulling out the food scale or the bathroom scale sounds like something I can do. I'll even keep track of when the week begins so I don't let it turn into a longer stretch: "Oops, has it been a month and a half already? My, time flies!"
It also sounds like a gentler, kinder thing to do to myself than what I was thinking about last night, which was fasting for a few days. Seeing denial of food as a form of self-punishment for the "sin" of failing to lose weight quickly enough to suit me is emphatically unhealthy. The fact that it was starting to seem appealing to me is appalling to me. If I could successfully punish myself thin, I'd have been slim for a while.
It has definitely gotten warmer here--in New Orleans, summer has arrived already--and one thing I have slacked off with slightly is my water consumption. Thanks for reminding me that it's even more important when the weather gets warm.
SO! I've written it on my dry-erase board, my calendar, and a Post-It on my computer: "Diet Break Ends June 5!" Until then, no counting, no weighing of food or of myself, no going overboard, just taking my first real break since I started. Even if it doesn't break the plateau, I think it'll restore my ability to deal with it with equanimity instead of *****iness and tears.
My poor husband; he has suffered so over the last week. He'll be happy to hear of the Big Break.
Thanks again, folks. I could never have imagined how important the support, advice, and expertise I find here is to success. Love y'all!