Is Nutella safe for consumption, and is eating foods that contain potentially harmful ingredients, with that knowledge, considered self-slaughter?

The basic principle regarding things is permissibility. Whatever foodstuff has not been proven to cause clear harm by the testimony of experts and specialists, its consumption is permissible and it should not be compared to definitively prohibited things. Remembering Allah and saying "In the name of Allah, with Whose Name nothing can cause harm" is good, but it does not permit eating what is known to be harmful. The questioner is advised to abandon delusions and not pay attention to them, because indulging in them leads to great evil.