A Friend's Mental Problem. Help!

Hello. It's about my best friend who has a mental problem and I want to know more about her condition, because I can't find a suitable explanation on the Internet (not one that corresponds exactly to what she has). So I decided to try here, I will be happy if someone knows exactly what her condition is, and whether there is a solution. I'll start with a brief description of her past to get some idea that might be helpful. She is 16 years old, 10th grade. Her childhood is not good at all, it is about problems between her parents - constant quarrels, shouting, even violence between them in front of their two children - she has a younger brother (with an illness, she is being treated abroad). Subsequently, her parents separated and now, for about 2 years, she lives with her father and her sclerosis grandmother. As a child, she often fell victim to the constant outbursts of her alcoholic mother, who became arrogant, depriving her daughter of many things, forbidding her to go out for no real reason, not providing anything a child needs. The rest of the time, however, he is a radically different person - a joker who gets along with others. She did not have such problems with her father, although he was one of the drunks. My friend is an artistic person - she has been devoted to art since she was a child, she is skilled, she learns quickly, so she is always good at everything she does. She is extremely smart, I don't speak at school (although I do well there). Can judge everything, quickly adapts to innovations. She has a little low self-esteem (not to such an extent because she knows what she is, she knows she has nothing, in fact she is quite beautiful), due to the fact that just anxiety follows her everywhere. We have known her since we were little (I am a year older), she has always been smiling, cheerful, with many friends, despite the problems in her family. Apparently, however, they influenced her on a subconscious level. I will try to explain briefly what exactly the problem is. She has no emotions - she is never happy or sad - she only experiences a momentary state of elation when something makes her laugh, for example. She doesn't care about anything at all - she is told that a relative has died - no reaction (at least not internally, in fact she pretends to be at least a little interested in front of her relatives, no matter how crazy she is). It would be the same if it happened to friends or even her parents. She doesn't care about anyone - she is antisocial, she hates people, she hates talking to them (but she can), she avoids them. For example, she would never enter her entrance with someone else - she always waited for him and then it was her turn. There is no problem with communication, she is not exactly antisocial because she has friends, but after a long day spent with them, she becomes exhausted and needs a break from her false behavior - the other problem. She claims that no one knows her true nature, which she herself does not allow to come to light, because in reality she is a bad person, but she can control herself. Without this control, she would certainly have resorted to violence, because for a long time she imagined how she hurt people in her head, even killed them in a cruel way. She wouldn't actually do it just because it would have bad consequences for her - the only thing stopping her. She's not a psychopath because she wouldn't enjoy hurting (or sympathizing), she just wouldn't care. Her eye will not blink. In fact, she says that everything written about them describes her. There is something else - for some time now we have found that there is something like a split personality - another person in it - it is this bad nature that hides all its emotions. She appears when something threatens her - for example, if someone attacks her verbally, she becomes so rude in her words (using only truths, however) that she is even able to make the person cry. (It didn't happen to me because we are more than that - our friendship is strong, as it always has been and we don't allow it to happen, we don't have occasions, we share everything, we trust each other, we don't have problems between us. I listen, especially if she talks about it, I ask her questions, I try to help, I get the same) She knows people, even if she is not close to them. He knows who he is, just one look is enough. He reads them. We come to the essential problem - foreign thoughts settle in her head - most often negative, coming either from her close friend - suffering from depression, or from the boy she loves - with the same condition. She herself claims that there is no problem with these thoughts. Although they often confuse her and delude themselves that they are hers, she quickly realizes what is happening. They don't bother her - she doesn't care about anything, nothing can negatively affect her. There was also a period when he heard voices almost constantly, not understanding what they were saying. They appeared when he did not speak and he could not control them, but later they decreased, now the problem is the intrusive foreign thoughts. This is confirmed to be the case by the girl to whom they belong. She promised to take me to a psychologist in the summer, she refuses to go earlier, simply because she doesn't feel like it, and she's not ready to talk to anyone either (in principle, not about her own problem). We searched a lot on the Internet with her, there are diseases, or more precisely conditions that correspond to hers, but only partially. We also learned that this lack of emotion can be changed with medication, but she says that because it doesn't bother her (nothing ever bothers her), she didn't need to be treated. I think that this gift she has is quite stressful, and she would be better off without it. If he finds a way to unlock his emotions, maybe reading other people's thoughts (which happens at certain times, not always) will be dropped. Because at the moment, due to the lack of her own emotions, she accepts those of the people around her (most often these two people). There are many things we cannot explain and we are looking for answers, but we cannot find them. I really want to know what's going on with her - at first glance an ordinary girl, but in fact much more than that. I hope I haven't bored those who have reached the end. I would be very grateful if anyone is aware of what is happening, even if I have not described everything in detail, I can answer questions, if any. Thanks also for your attention.