Most Helpful Girl
Run away from the new girl. Reinvest your energies in your marriage. If you keep talking to the other woman there is absolutely no way your marriage will work. Either that or file for divorce. Those are your only two options.
Keep in mind that if you choose to end your marriage with zero attempt to work things out, you're setting the stage to repeat this cycle over and over and over again.
Most Helpful Guy
The logical thing to do is to get a divorce and pursue the new girl. What you will really do is likely different.