(This is just an idea for an ending to a post-apocalyptic novel that I'm writing. I've asked other questions about this story before.)
In a post-apocalyptic world, my MC Eris and others like her have been exposed for their whole lives to radiation that has given some of them strange powers, and Eris has the ability to manipulate life force. As a girl during a fit of rage, she accidentally killed her family by projecting her powers, and has very little control over them. As a possible ending, I want her to lose control again and kill all her friends, then move on to a paradise-like city named Eden (I know, it's cliche, I'm working on it). Perhaps I will have this novel be stand-alone and leave the reader to imagine the havoc she will wreak in Eden, or maybe it'll be a fresh start and the next book will be her dealing with the consequences of her actions and navigating Eden.
The thing is, though, there's already so much death already. First of all, very few humans are even left on Earth due to a nuclear-holocaust-type event (think Cold War mutually assured destruction) that happened around this year in the book (story occurs in 2212). Second of all, Eris murdered her family and other survivors who came to investigate, including the wife of the story's antagonist.
Is a gruesome ending simply not necessary? Should I ditch this idea entirely?
I'm not asking what to write, I'm just asking if what I have written and thought of is appropriate for a post-apocalyptic novel.