This may seem like bait, but I’m asking a genuine question. This happened to my girlfriend where she rejected her former best friend (in a nice way, even saying they could still be friends) and later got insulted, told to kill herself if she was so depressed, and said she never wanted to see her again. Some people say this girl is mean, crazy even, and others say she had the right to say that because she was hurt and my girlfriend should have said yes even though her best friend was a lot less mature and younger than her. They were more like siblings than anything.
‘Normal’ doesn’t mean much.
A more interestigng question could be: is that what she wants to do? Is that how she wants to be? Acting like the dude that insulted her may very well not make her feel better the slightest. Quite the contrary, it can easily make her feel worse: realizing she behaves in similar way as that other person which, imho, should not be considered a role model.
Artists will often use their own frustration, pain and anger (against anyone/anything) as a drive to create things that are not insulting to anyone, that sad destructive energy being transformed into art. Maybe it is something she might want to consider?