NTA. An adult is responsible for the things that come out of their mouth. I say this, and I am diagnosed bipolar. I am subject to intense, irrational rage, focusing on small things until they are huge things, and I have a talent for thinking of the most hurtful things to say and using the truth like a razor. I have been battling this for decades and if I lose control and say some shit, I know I have to accept responsibility for it afterwards.

It doesn’t matter if you don’t mean what you say. You still said it. It will echo in another’s ears and mind, and just in the intrinsic way communication functions, every time I act out like this, I fatally crumble the trust of those around me. It is incredibly hard sometimes. Sometimes I fail. Still, there’s no one to blame but me. Your girlfriend needs to grow up.