It is so true that the most dangerous time for a woman in an abusive relationship is when she is trying to leave.
Someone above posted that they wished she could have just taken the kids and run. While that is very likely what she would have liked to do, it's just not a good move, in the eyes of the courts. If she did that, she would likely be the one to lose custody and then the kids would be full-time with the scary husband.
I've known people in very similar situations and it is a horrible position to be in. You have to kind of 'ease out' if possible to keep the upset down to a minimum. It is wrong wrong wrong, but a scared woman will often comply as much as she can to minimize the fallout.
Sometimes it works and sometimes, as in beautiful Crystal's case, it doesn't. The main point is that the fear is real. Especially when he's threatening the kids. I would think that would have given her some legal teeth though...
In no way blaming or saying she deserved to be hurt or killed, but I am a little surprised that she was dating and having overnights at the BF's house before she was completely away and safe (as safe as you could be) from this monster. In such a dangerous situation it's like waving a red flag in front of a bull. I totally see why she chose to stay there until her place was done, if he was making threats against the kids. It's a way to appease until there is another place to go. Sad, sad, sad.