I'm going to tell my gf I'm pro choice
How are you supposed to be pro-choice?
It's not my fault, it's in my nature.
You are a good potential partner if you can discuss such difficult issues with them. But sometimes these things are unwanted, and can cause a lot of tension between you two. So make sure that you only discuss these things when they are open.
I'm excited to make her upset.
OK, discussing politics is good for your relationship. But saying something just to get a rise out of her is wrong.