Ugh, update.....
I've been in VA for the past week, but before I left, I poked my finger into the bottom of the cactus's pot and felt a soggy plastic bag. So I started pulling it out, it was like those clown hankercheifs...just kept coming and coming...I ended up wrapping the guy in blankets and smashing the clay pot. Inside was 3/4 of muck and 1/4 of cactus roots. People just don't understand cacti at all. How the barrel cactus lived this long in her care, I have no idea. I have it sitting in a pot drying out with just coconut coir after I sprayed it down with sulphur. I hope it doesn't rot. Sigh.