edgey

Koku, The mold your refering to is Mycorrhizae. This is a symbiotic parasite (fungus) which attaches itself to the small roots of host trees. Both the Mycorrhizae and the tree gain from this relationship. It usually looks like a white web like substance. Your photo showed a wealth of the stuff and unfortunately you've washed it away! If you have any of it left get it and mix it back into the soil. Its an easy mistake to make to think of it as a disease. Live and learn. The tree might be ok?
Keep it well sheltered over the winter. Bit early for mugos, Beginning of spring is best here in oz for repotting. The soil pooling is a worry, fast draining mix is needed for pines. Mix some river sand into it.
Hard to tell about the tree, No visible trunkline, just a mass of branches. Might be a yard candidate. Good luck with it Andrew