Locke tells Kate he had a crazy mother, now Claire is one too

Back near Locke's camp, Kate is sitting alone amongst the trees crying. Locke comes over and apologizes for the incident with Claire and says that he told her the others had Aaron to give her an enemy to hate, therefore something to live for. He then promises Kate that he will keep her safe just like he promised the rest of the group.

Locke then takes Kate down to the beach where he shows her Hydra island and tells her that's where he sent Sawyer. He tells her that he is not a "dead man" as she referred to him earlier. He tells her a long time ago, before he looked like Locke, he had a mother who was crazy. Because of that, he had some "growing pains" which he is still dealing with and could have been avoided if things had been different. He tells Kate that he told her all of this because now Aaron has a crazy mother too.

So how much of Locke's story can we believe? Did he actually have a crazy mother, or is he telling Locke's story, because Locke's mother was certainly a bit looney? Locke did get emotional during the story which would lead one to believe he's telling the truth, but you never know because he seems to be a master manipulator.