NTA, but equally I don't think you should pick a Holocaust book as your intro choice to the group. Choose something less heavy as your first selection and get the lay of the lan more.

Once you know the group a bit better, you'll know what they can cope with and what they can't. I'd feel a bit wary about someone bringing in something so heavy first up, I'd assume it's all they care about and that they'd be a total buzzkill to the group as a whole.