The Texas Advance Directives Act, Section 166.049, provides that "a person may not withdraw or withhold life-sustaining treatment under this subchapter from a pregnant patient."
Look, if I was in the shoes of the husband or family, I truly do not know how I would feel. I haven't been in this situation.
Getting back to the law though: in the above quote, the Texas Advance Directive specifically mentions that the patient is pregnant. Why does there need to be a mention of prenancy, if there is no difference, legally, between a brain dead pregnant woman or one who is not pregnant? There is a difference.