Beginner Q, new to winter rests -- is this Den pierardii going dormant or dying?

[Surrealle]

Awesome, thank you for the info! I haven't been letting it get bone dry (makes me too nervous!) but I just wanted a sanity check that I didn't cause damage either with reducing the watering or repotting. It is near a south window with supplemental light, and my room has been getting colder at night, so as long as it looks okay in the photos I'll keep plugging along with what I'm doing.

Thanks again!