It's obvious there is still a bond between the two of you. It would be a tragedy if a physical condition would be the culprit in ending this love covenant between the two of you. And yet, at the same time, it's as you said . . . the ultimate will of the Father is that we be able to literally "live" in the peace that only comes from Him and living in physical bondage and fear is not an option.
Many will try to enforce marraige vows when things go wrong . .and to an extent, that's not always a bad thing. But when the other is no longer able to uphold their side of the marriage, then regardless of how strong the other is, the marriage can not sustain it's strength by only one person holding to their vows.
I would not advise getting a divorce just yet, but a separation may be in order for a short time. The husband may need to see that control is not what makes a marriage and once you show that you are serious about making a change . . .he may be willing to get some help not just with the depression, but with the abusiveness he's brought to the marriage itself.
If you do separate for a while, don't make it a secret . . . if he choses to become violent against you for leaving, he needs to know others are aware of things and are supporting you as well as protecting you. If you separate, keep your words toward him on a constructive level. Let him know that this is not because you don't love him, but because you can no longer allow him to abuse you. And if he refuses to change, then you can refuse to return. Separations are not healthy, but neither is remaining in an abusive relationship. Obviously, something is broken . .and until change is introduced to the situation, it will remain broken.
You're in our prayers always.
In fact . . .
Father, we come to you with this situation that is beyond our ability to fix. Your hands are hands that heal and so we release this into your healing hands and give this man over to you. I pray that peace will return to Nancy in such a way that regardless of what happens here, she'll receive your strength and comfort so that not only will she survive this time in her life, but she will flourish because of it. Let her feel your presence. Let her know she is loved by you and your promise to be with us to the ends of the earth applies to her as well as anyone. Take her under your wing father and let not the enemy remove her joy any longer. Our hope is in you oh, Lord . . .in your name we declare that she may rise from this and give you praise as she goes through this darkness in her life. Let your light and your love shine upon her right here and now Oh Lord . . .In your nature and in your name, I thank you for answering the prayers of the saints . . .