Repotting phal w/ mushy roots

[Stoniegirl]

Hi everyone. I bought this phal several weeks ago on clearance at Lowes. At the time she had a broken flower spike but was in otherwise good condition. The leaves looked great, no visible problems. She did look a bit root bound, the roots were tightly wound around the inside of the pot but were mostly green and firm. I had been putting off repotting her because she was so tightly packed in and I did not want to break the new flower spike. After a few days at home I noticed small insect crawling around in the pot and the condition of the leaves had began deteriorating. I treated her with a mix of 50/50 alcohol/water and cinnamon oil. I have not seen any pests since. The roots have been gradually turning brown but still looked firm. This morning I checked on her and she had white fuzzy mold on some of the tightly packed roots. I decided that she need to be repotted. I removed the old medium (found a small snail). Root are mostly firm although a lot of them look broken in multiple places. I removed the mushy ones. I am at a loss on what to do next. Not sure if I should repot her in to a bigger pot or the same size she was in? Should I cut off more roots? Please help. Any and all suggestions welcome. Thanks in advance!