She grew up with the same core beliefs that he did. They both attended Freed Hardeman University, a university affiliated with the church of Christ in west Tennessee. There is no hint from his family background that he would be abusive. Anything is possible, but those that know both of them from college and in recent years are stunned.
I know someone from TN, and there are a lot of Church of Christ churches down there. I've heard that denomination is just a tad "off" as far as being insular, requiring people to marry within the denomination, etc., kinda like a cult would. (I'm not calling Church of Christ a cult, but it has some of that flavor according to this person I know.)
As for post-partum depression, from what I understand it is due to hormonal imbalance. When a woman gives birth, the levels of progesterone plummet dramatically. It is NOT feeling a little blue. Hormones can have a huge effect on the brain. Back in the 1800s they used to put menopausal women in institutions because they thought these women were nuts. We're not nuts! It's the hormones!
I also think there are known cases of people on anti-depressants killing, either themselves or others. I personally don't trust the big drug companies or the FDA to keep us healthy and safe. Remember Vioxx?