Pretty much this. She might be sad, but just as sad as Naruto and Kakashi, but only because she lost a former comrade. Nothing more than that.No, she wouldn't be mad at all. Naruto would only kill Sasuke if no other alternatives were left during their fight. She'd understand that Naruto tried his best. However, of course she would be sad for a while, just as Naruto himself would be as well as Kakashi.
Missing the point of the thread and the BIG IF HE KILLS SASUKENaruto killing Sasuke doesn't even exist.
If Naruto does kill sasuke, then that make Naruto not becoming hokage more useless than ever.
If he had to chose weather he'd kill sasuke or become hokage he would probably chose to die or neither.