The only way a JW can divorce is if their partner has committed adultery. For JWs, it's called scriptural divorce. You cannot ask for a divorce if you're the guilty party. She can divorce in a court of law but the JW won't recognize it.
You mention she is being shunned. Has she been disfellowshipped? If not, I doubt she is being shunned.
It takes years if not decades to break free of the JW's cult mind control. Get ready for the roller coaster ride and the mind games. Even if she leaves to be with you, the guilt will continue and she will be continuously torn inside. JWs believe the end is just around the corner and if she's not a witness when that comes she's dead meat. It takes years to get rid of that mindset and it's very strong. You have no idea the fear it creates. There's always going to be that back and forth between her trying to be saved and destruction. She might be able to push it in the back of her mind for some periods but the guilt and fear eventually come back. If she leaves, get her into therapy ASAP.
I've done some crazy things because of love, so I can empathize with you. Good luck.
Oh, and one more thing. JWs are trained to be very good liars so watch yourself.