I haven't progressed that far in the msq so I can't comment on that specific battle but at times I've felt the same, as far as having hit the limit of my capabilities. Maybe I already have and get through with my husband's support, because he's naturally more adept at anything that requires quick reflexes. I struggle to process what's happening on my screen in time to react appropriately. My enjoyment of the game is primarily the immersive environment, but the msq happens to be an extension of that.
Anyway, mainly I just stopped in to say that as someone who often feels frustrated because knowing what I'm supposed to react to and actually accomplishing it are two different skills, I can relate.