@ZeroExe1,
If you want to end your relationship with your current girlfriend, then do so. Don't keep her on hold or any such nonsense. And you don't need permission from your best friend in order to do this. That should happen regardless of whatever else happens. And be nice about it, okay? Because breakups stink and your current girlfriend deserves your kindness if nothing else.
Then, contact your best friend. Don't go in with confessions of love. Instead, say something like, "I broke up with ____ because I could not stop thinking about if you and I could have something. I think we can. What do you think?"
And then wait for your friend's response. She might agree with you. She might freak out. She might insist you are only friends. She might tell you she's found a boyfriend at her new home. She might even tell you she's a lesbian.
But what I'm advocating is to be open about things but still give the ultimate decision to your friend who, right now, doesn't know what is going on.