I'm thinking of crossing a line I never thought I would
Why do you think that it is a good idea to cross this line?
Because she's a piece of shit who deserves to die.
Even if someone make you very angry, you should never consider physical violence or killing. There are serious consequences for crossing lines like that, so you would be better off practicing self-restraint, no matter how angry you are.
I do not agree with what you said. I'm going to hurt her because she doesn't deserve me being nice.
You should not cross that line. Once you cross a certain point there is no coming back from it.