Here is the one pad that was remaining. It is worn a little funny but I think that is likely due to the 10 blocks or so I had to drive to get to a safe spot for the tow truck.
https://photos.app.goo.gl/8DVHUieY8CxW2WiV2
I took everything apart last night. 2 bolts holding the caliper to the slide pins were tight
2 bolts holding the bracket to the hub were tight. Piston in the caliper moves freely
Slide pins move freely. All pads on each corner were around 3/4 life left. My original guess that they were getting low was wrong. My original guess was just looking at the spacing without actually removing the caliper and checking the pads so now I know that just a visual wont give you any indication of pad life.
Here is the original photo of what I saw on the side of the road after hearing the loud pop.
https://photos.app.goo.gl/LfuGUedYCfEZkV963
Let me know if the links don't work and I will try a different photo hosting site.