I love to win arguments over text with my gf
Why do you love winning arguements?
I love to piss her off
You shouldn't expect to always be right in an argument. Your gf is gonna be upset if you're intentionally pissing her off.
It is not just to piss her off. I'm showing her who's in charge and that I'm the only person in the relationship that matters.
Your reasons to always want to win seem wrong. You cannot be right all the time and expecting it to be so will cause you pain when you find out you were wrong.