Could have been rape. The text message was from December. Just cuz' it was consensual at one point doesn't mean it was consensual at the point in question.
How would this play out in court if the sex was consensual, however, due to abuse in the past she could legitimately say she feared for her own life?
Also why isn't the husband being charged with murder. If the guy was driving away it isn't self-defense...is there another classification (justifiable homicide?) which would allow for his innocence under the law?