Murder or self defense?

I recently viewed a documentary film on HBO, called Every F@#$ing Day of My Life. It was about a young woman, with four boys, murder her abusive husband with the help of her seventeen year old son. She married her husband very young, (17) and it was after a year or so into the marriage, they had their first son, Randall. Who by the way, is the one that helped his mom murder his dad. She finally snapped after years of abuse, and without hesitation she picked up a hammer and a small hatchet, and they bludgeoned him to death. Surprisingly, she called 911, immediately, and admitted to doing it, mainly for her four young boys. The seventeen year old did not make bail, however the mom was released to be there for her other boys, but she had to turn herself in on a specified date. She was a woman that was abused for about twenty years, and she couldn't find a way to escape. In fact the documentary revealed that on the night of his death she called the police, due to the abuse, but they left without further investigating. The husband stayed inside with three of the boys, and he demanded that the mom and the oldest son get rid of them. They reluctantly obliged, but before the police could fully leave the area, neighbors tried to get them to go back, but of course they refused. Eventually, they did go back later on that night, but not to help a frightened battered woman with children, who were also abused. On the contrary, they came to retrieve the body of an expired, abusive, ruthless, cruel man. Even though she was clearly the victim, it was not her place to destroy, that which she did not create. I was very saddened about her demise, and I can't figure out for the life of me if she really tried hard enough to get away, or if she ever notified authorities before that fatal night. So, when it comes to defending yourself,and your children should the victim/murderer be pardoned or recieve a less harsh sentence than ten yrs.? Which by the way, she recieved one hundred twenty mo. and her son recieved seventy-five mo. The son should be released Aug. of 2011, and the mom is up for paroel in 2016. So, now that I gave you the shortened version of this story, do you think she was justified, or do you think she was cruel and heartless for taking someones life, no matter how much he hurt her? I know woman and children are in this situation every single day, in fact my sister went through it as well. I truly empathize with her twenty year long ordeal. I can attest that I will never know how it feels to be trapped and abused by someone who said they love you. What I am baffled with is the fact that the fear can be so overwhelming that it paralyzes them and they remain a prisoner. Please respond and help me to further understand the paralasys a victim endures when thier childrens lives are threatened as well as their own.