I survived the dinner. Actually I did VERY WELL, if I may say so. I was able to stay in Spanish the whole night, only needing to occasionally get a word or two translated. But what was more important was the confidence to barrel forward in a sentence and let it out of my mouth.
It was a pretty small group, and the native speaker was very kind and accommodating. The other "guest" was a bit of a talker, and liked talking so much that he frequently just spoke in English, which seemed to be contrary to the spirit of the evening. I tried to keep us in the realm, but for a good 15 minutes in there the host and the other guest just went off on a long conversation in Ingles, while the native speaker and I sat patiently and enjoyed a little Mezcal.
I left the party quite pleased with the work I had done, and with renewed confidence that I really can communicate in this language.
Now that my Spanish Crisis is complete, I'm going to allow myself to put Spanish back into the rotation, and get back on to Chinese and Japanese again. So watch for more variation again!