Dear concerned friend, I concur that the voice of “Maggie” is problematic. You are right to be alarmed. It may signify that she is experiencing psychosis which is a break from reality. “Maggie” is concerning because it is “commanding” her to behave in a certain manner. As you mentioned it’s controlling many aspects of her life, to the point where she has had a physical reaction such as nausea.
The type of treatment she may require will depend on factors such as how long she has been hearing voices and if there are other symptoms that accompany the voices. She may benefit from individual counseling, family counseling and possibly medication.
As a friend you should be honest about your concerns. Suggest that she speak to her parents about “Maggie.” If she does not feel comfortable with this, offer to inform her parents or go with her when she tells them. You could also tell her that you did some research and learned that it’s not normal to hear voices. You could tell her that when individuals hear voices it is strongly recommended that they be evaluated by a mental health professional. If she asks how you gained this knowledge tell her you wrote to a mental health professional.
Also, you shouldn’t be dealing with this issue alone. It may be very serious. You should talk to your parents about how to help your friend.
Your friend is lucky to have someone who cares about her wellbeing and who recognized that “Maggie” may be a problem. You’re not only a good and caring friend but you’re insightful and intelligent. It is important that your friend be evaluated by a mental health professional. If she is experiencing a psychological disorder then early treatment could prevent it from becoming worse. I hope that your friend is able to be helped. Please be well.