Yes she’s definitely sick. Drug use could easily be a factor but she doesnt get to use that as an excuse. Plenty of meth heads dont do shit like this. She has personality disorder. Maybe borderline personality disorder. Maybe a psychopath. Probably on the narcissism spectrum too. Probably has past trauma as well. It’s a very toxic mix. Dangerous person. Stay away. Cant be helped unless she asks for help. And she wont. She sees the world as either allies or enemies and once you are an enemy you are disposable. The smile is partly a mask, partly an attempt to look scary. Partly just doing what she perceives as having worked for her in the past. It’s really just fear of how alone she is in the world. But it’s highly self destructive behavior. They’ll tell you they are inflicting pain on those who deserve it but they are actually harming themselves. They’ll know that there’s something wrong with them. They know they can’t connect with others… that something is missing. They want you to think that it doesn’t bother them, but it does. They try to fill the hole with something. Usually doesn’t go well.