Dare I do this? I'm going to tell her I didn't want to talk to her
Oh no, you can't be serious. Why don't you want to talk to her?
I'm pissed off at her at the moment and she's annoying.
It's reasonable that you don't want to talk to her right now, because sometimes people get annoyed with other people. It's fine that you tell her that you don't want to talk, because being honest about how you feel is a good thing.
Nah, I'm going to be jerk and tell her that she has a fat ass and she's boring.
You can decide not talk to her if you want to. But leave out the vulgar talk, being rude is not going to make you look good to anyone. She might tell everyone you said this and they will never talk to you either.