Do you mean what you say when upset?

I always wondered this because pwbpd - girl I know, constantly claimed she didn’t mean the things she said when upset. It sounded genuine but It always left me confused why say it in the first place. I feel like she had to have these thoughts/ beliefs before, in order for them to appear when she’s upset.

So, those of you that resort to foul language when upset / splitting (verbal abuse) - do you mean nasty things you say? Where is it coming from and what is your thought process? Also, I feel like (outside of bpd) once someone crosses that line with someone, they will just continue doing it. I call her out on it and of course she will say she didn’t mean it and sorry and tries hard until something upsets her and repeats it again.

Abuse to me is of course where relationships end - however since she’s committed to getting better and is otherwise a good person I know is struggling - I’d like to hear your thoughts. Especially those self aware and in treatment / remission - is she’s doomed to repeat verbal abuse once getting away with it no matter what? What do they teach in treatment regarding such behaviour and did anyone manage to stop it entirely with the same person?