Wow ! You got fungus problems or bud rot bad…Myself I would separate it from the other plants before it infects your other plants if it hasn’t already.
It looks to me that it went on way to far to save. I would be checking " REAL GOOD " any plants that were with or near this plant. Just to be on the safe side I would
If you have already gotten some kind of fungus there are things you can use: neem2, neem oil works wonders!! Potassium Bicarbonate, Baking soda and for other chemical agents you can use Plant Shield, Serenade and pythium! There are many other chemicals and organics that work but these are the most popular and they work very very well