It is very heartbreaking ThoughtFox, what I dont understand is how could Kate be sick of dealing with her children if they were in creche for the most part of everyday, the parents had a lot of me time but not a lot of kid time.
She still would have been involved in daily routines such as getting the children up and dressed, getting them to eat at mealtimes, giving them baths and putting them to bed. Those times can be the most trying times of all for parents, even when both parents are involved and the kids are generally well-behaved. They are all favorite battle and meltdown times for kids.
Add to that equation being in a strange place, a father who sounds like more of a playmate for his children than a help-mate to his wife, a child with behavior problems, and three children under the age of four, and I get exhausted just thinking about it. I can understand how Kate must have felt very frustrated, especially if she thought of this time as her vacation, too.
I recently read an article that that talked about what a great father Gerry was and gave as an example that on the evening of May 3, while Kate fed the twins in the restaurant, he had Maddie nearby on the beach, playing with her, and she was laughing and shrieking "Daddy! Daddy! Daddy!" Anyone with children knows the worst thing you can do with a child right before bed is to rile her up with a lot of horseplay. A good and responsible father would have taken her back to the hotel, given her a bath, and read her a few stories to settle her down, giving her some quality one-on-one time.
If Kate did lash out at Maddie at bedtime (and I know that's a big if at this point), she might have actually been more frustrated with Gerry and sick of the situation in general, and simply took it out on Maddie when the child refused to settle down.
I may be in the minority here, but I do think it's possible for a good mother to snap.