Drop the idea that the marriage is the problem, and then you will be able to look at her as an individual. Drop the image that she must be a wife, and then you will be able to look at her more sympathetically, more intimately.
Look at your husband like you would look at a stranger. He would appear less of a demon then. Look at your wife as you would look at a woman you are meeting for the first time. Is she still the vamp of your nightmares? Do you still shriek out upon looking at her face? No. You might even fall in love again—and this time it would be a rising.