So after several days, a lot of chocolate, and a little bit of alcohol, I finally felt (mostly) not upset about my mistake and was able to re-start Eris. Here is the collar, half done and with the stitches picked up to start the second half.
Irritated as I am, I really am glad that I re-knit this. The first try had several small mistakes that bugged me but not enough to make me rip it and start again. Once I discovered I'd used the wrong gauge, though, I obviously had to re-do the thing. This time around I was more familiar with both the chart symbols and how it looked on the needles, so I caught mistakes right away and could fix them.
I'm much happier with this collar.