After work I took care of sick wife by making her some soup, then headed to the garage to take a look at the full extent of the damage to the XS. I'm not sure HOW it happened, but it looks like the brake rod wrapped around the wheel spacer and then snapped. Maybe it somehow snagged. Bizarre. I was lucky enough to be going slow enough to not wreck.
The brake pivot, brake rod, and brake plate lever all got damaged or destroyed. I managed to pick up a new linkage for $10 off ebay. I have only tonight and tomorrow to get it fixed or I'll have to ride my KLR to Throwback Thursdays. A KLR is not very vintage.