Well.. this does not look good.
Looks like some fungus.
What I would do... I would cut that part off like 2-3 cm above (above that yellow part). Also cut then big damaged leaf off. That one spot on the top leaf - you can observe it and if it dries up and doesn't get bigger you can probably leave it. If this is fungus it might spread. Cut it off!
After the main middle stem is infected there is almost no way to save it.
Cut the dried and damaged flower stem. There is no use for them.
I would also cut down the ones that do not have any buds so the plant doesn't get tempted to grow new flowers there and doesn't lose energy. Better for her to grow some new leaves now.
Roots look good. She will be fine :) Just a bit butchered.