What happened to this leaf? and what should I do?

[wism]

Don't pay attention to the cut, the orchid fell down from the table and the sick leaf has broken.
Is a new leaf (1 month) and during this time the plant was outside on the balcony. I sprayed a fungicide on it but did not help.
The plant is still beautiful and continues to grow, maybe it's a bit stressed one keiki and another leaf were born, instead of a new spike.

I'm afraid that it will infect the rest of the plant. Is better to cut the leaf?