She was whacked over the head by Tom during her first appearance. Walked away from that. She tried to kill herself, but survived that. Now she's survived being shot in the head! She's either damned lucky, or indestructible.
Don't forget that she survived the gloved hand killer (Lindsay) twice! Most victims died first time around. Diane was another survivor I think.
But I've always liked Esther so I'm glad they didn't kill her off. However I did see in the spoilers that 'she will never be the same'. So whatever that means I guess there is more drama ahead and probably a breakdown with her marriage to Kim.
Who I have to add I think is still a bit bonkers. Who could really trust someone like Kim, given her history?