I strongly urge you not only to maintain your marriage, but also to make it grow even stronger during this difficult time. That may sound impossible—but with God's help, it can happen.
Why do I say this? One reason is because God gave your marriage to you, and you both made a vow to Him that you would be faithful to each other no matter what happened. Yes, I know divorce is very common today; hardly a family is untouched by it. But God's perfect plan for marriage hasn't changed: "Therefore what God has joined together, let man not separate" (Mark 10:9).
But another reason I hope you will keep your marriage intact is because your husband needs you more than ever right now. No, you can't be together (although I hope you will write and visit as much as possible). But he needs your encouragement, and he needs to know you care. Some of the saddest letters I receive are from prisoners whose spouses or families have rejected them.
Most of all, I pray that this will be a time when you both draw closer to God. You don't mention your husband's crime—but no matter what it was, God still loves him, and Christ stands ready to forgive him. Pray for your husband, and make Christ the center of your life as well.