There is only one possible scenario in which I can remotely believe that she felt any fear, but it was not fear for her life or that of her children.
I think PF has something on her, something big enough that could have destroyed her professionally and she chose to help him rather than be exposed. And, deep down, she wanted KB gone even if subconsciously for her own selfish reason.
I firmly believe there's much more to all of this because her story, as put forward by the R's and M, just doesn't add up on any level.
I also suspect there's a possibility that PF may actually be fearing for his life. Hear me out. Just say, what if someone that really loves her wants to protect her from that info and any other dirt coming out during PF's trial? This rabbit hole may be much deeper than any one of us can imagine.
OR
Just my fertile mind going in all directions
It may no longer be a valid theory as it appears she has lost her license or is about to. Then again, maybe it's something that would take away all hope of ever getting it back again. What does PF know about her that she does not want revealed? JMT