She is a youngish, somewhat attractive woman who chose of her own free will to marry and bear the child of a man with very, very few redeeming qualities, perhaps the fewest a man can have w/o actually being a villain. I'd say that basically any reason given for why she is that way could prolly be answered with a quick 'Yup', and stand better than average odds of being on target. But I would use 'retarded' in that she prolly smothers all thought processes she actually may have. I think most people actually born with mental retardation would use what wits they have to recognize Cotton as someone to be avoided.