I think you sound like an awesome friend.
As for crying all the time, I know with all three of mine, I breastfed, and it took FOREVER in the beginning. By the time they were done an hour if not more later, and even if it had been two or three hours between start to start feeding (and never was it three hours- still isn't and he is four months almost), I only had an hour to recoup and it passed way to fast! Hence, he was crying all the time.
She sounds like a normal post pardom mom to me, but if she starts really acting depressed, not just overwhelmed or tired, or starts talking crazy talk, do not hesitate to get her help. Just keep a vigilant eye on her.
One more thing...my kids always went longer between feeds and slept longer if we were out and about, so if you can get her to the park more often, I think that the companionship and sunshine will do her a world of good. I would just feed as needed in the air conditioned car....