All up to you.. you and your gfs opinions are the only ones that matter

True enough; however, why not stimulate and arouse each other the way nature intended males and females to do? Porn is not real. Your girlfriend and her boyfriend are. Spend time becoming "tuned into" each other, not trying to have some actors and actresses to get you aroused.

Know, also that porn is mostly for the male of the species not the female. The videos are designed to get men aroused and excited, not so much the fairer gender. That said, why not learn how to become aroused and excited by what both of you do when together? Anything else seems artificial and contrived. Later, after much practice and much time learning about each other {read: months) if you want to enjoy an X-rated movie, go ahead, just not in the beginning of a relationship.

WHAT? Not unless you WANT to stop.
None of her business really what you do on your own time.
Do you ask her to give up readin "steamy novels" - no, of course not.
Well, pornography is the male equivalent of the "steamy novel".
I'd not even mention it.

Why do you feel you should stop? Would it matter if you masturbated to dirty thoughts instead?
BTW, If she seems sexually open enough you might want to share it with her.
My gf and I occasionally enjoy watching porn while stimulating each other and have wild sex afterward.