Should I dump my gf for to date this girl?

Stay with your girlfriend, please do. Even if you and your friend had chemistry you are in a relationship already. I doubt your girlfriend would dump you for a guy. If you broke up with your girlfriend she'd be sad, and think you are a jerk. So be a friend to your friend. But, don't break your girlfriend's heart. And stay honest and trustworthy with your gf. So don't cheat!