Hi Bud, welcome to the forum
That sounds like a pretty typical story with folks who really don't know how to care for them. To many flourist it's the flowers they are more important then the plant.
85 % of roots is alot to cut, but if you think you had to, then the 'chid is better off, it'll make new healthy roots.
I would cut of the spike and allow the 'chid to gain some energy and set new roots, very important right now. Give it good strong lighting (not sun) which will help it in faster growth & setting down new roots.
What did you pot it up in?
Agreed with the fungicide, sounds like good plan to me.