Somebody explain Season 4 to me please (spoilers)

I gave up trying to follow the plot halfway through. This is what I got: the woman who befriended Jack’s girlfriend and turned out to be the big bad hatched a plan to detonate biochemical weapons as some kind of demonstration, in order to sell said weapons to terrorists? And also presumably to hurt the USA and Europe because she resented rich countries? She used Myanmar drug producers and Mexican cartels to get the weapons to the USA? And she had the Nigerian president killed in order to make sure that the bombs could go through Nigeria on the way from Myanmar to Mexico? The former director of the CIA put together a secret operation to help her? Why?