How do you deal with this kind of person?

I am really hoping for some serious feedback. I have been really pondering this for quite some time. In my past relationship, I had some complications with the girl I was seeing. She would constantly be out of line and behave really irrationally and I'd call her out on it, and her typical response would be "Sorry for being so sh*tty." What would you have personally said? She acted very defiant, and it was so hard to keep up with her because she had a tendency to blow things out of proportion all the time. She'd constantly twist my words and try to make me the bad guy. Whenever I would try to stick up for myself, she would say "Sorry for being sh*tty." I had no idea what to say afterwards. I wasn't trying to belittle her. I was just trying to point out that the way she acted was unnecessary. How would you guys have acted in my situation? Thank you for listening