I wasn't using that as evidence, I just think it's a nice summation of her feelings.>I'm sorry it has to end this way, brother.>No you're not...
Azula's not sorry it ended this way because she's been prepared for this ending since literally her childhood. This is why she had a flippant reaction to his approaching death by Azulon, this is why she casually tried to execute him after not seeing him for three whole years during the B2 premiere, this is why she'd watch him boil alive with a huge grin at the Boiling Rock. Zuko earned his place back at the Fire Nation by helping her defeat the Avatar but as soon as she got a whiff that he was swaying sides she did something that, again, she knew could have ended in his death this time via Ozai.
Azula has no idea how strong Zuko's plot armor is, all these different instances could have killed him and she wouldn't have given a single shit. Well maybe than Zuko's ghostly image would appear in mirrors alongside Ursa when her mind inevitably started to go, not realizing what she'd lost until he's already gone.