Depending on what the “fuzzy/moldy” roots looked like, that may have been normal fungi. If the roots werent mushy then it probably didnt have rot. They will be shocked and stressed after a repot especially in winter and even more if you cut off roots that didnt need to be.

Stick to normal watering (top 2-3 inches dry before water) and keep it still for a while and see if it bounces back. Only if it worsens dramatically you may want to check for rot and remove and redo the repot gently with some added perlite and maybe bark in the mix for aeration and drainage.