I'm going to confront girls in my highschool about how they treated me before and after getting a girlfriend
How have they treated you differently?
Before I had a girlfriend, they wouldn't treat me as badly as they do now.
It can be hard to confront people sometimes but it is good to stand up for yourself. It will be harder for people to push you around.
In fairness, they weren't bullying me. It is ultimately petty high school drama.
I think you're definitely making the right call in confronting them about their past rude behavior towards you. I think it's great that you're being proactive and preventing such things from happening in the future.