It is normal to feel sad about the end of a relationship, especially a marriage. The great investment into marriage and the precious family it creates should rightfully be protected and the flippant dissolution of it should be avoided.
However, sometimes a marriage should end. In the cases of adultery, abuse, addiction, and abandonment, divorce is a real option that should not be disparaged or characterized as evil. In a society that seems often to elevate marriage to the point of idolatry, it bears repeating that God values individuals above institutions.
Yes, it is good to fight for your marriage. It is good to do all you can, including counseling, fasting, praying, and even separation, in the course of providing life support to such a significant relationship. A clean conscience before the Lord renders an unparalled and much-needed peace.
Sometimes the marriage does not survive in the face of the unresolved issues listed above. In these cases, it can add to the despair to characterize the dissolution as a loss. While the unsatisfied hopes, unrealized dreams, and sacrificial investments of blood, sweat and tears should indeed be grieved, it is much more accurate to recognize that the abused spouse was rescued.
God heard your prayers for rescue. Yes, you thought your cries begging for rescue would activate God's power to turn your situation around and you would be able to experience the beautiful marriage of your dreams, fulfilling God's design, but please consider that His answer was to rescue you out of the relationship. Trust that He knew your spouse was not going to change, was not going to yield to the guidance and healing of His Holy Spirit. Trust that He is working to preserve the purpose He has planted within you and He knew that rescue was the only answer.
Trust that God's will is for you to be loved and for spouses to provide a nurturing environment in which both individuals are empowered to accomplish the special assignments laid upon their paths.
You did not lose that relationship. You were rescued from it, released to fulfill your calling. Trust in His unfailing wisdom and that He is working everything together for your good and His glory.