Chantal worries that the neighbors are reading her thoughts and talking about them behind her back. chantal likely suffers from:

Chantal is likely suffers from paranoia. A person who is paranoid or has paranoia likely experience of having to be distrustful toward others in which is in an obsessive way or form as he or she worries often when exposed towards other people.

I believe the answer is: Schizophrenia

People who suffers from schizophrenia Would not be able to properly distinguish imagination and reality due to the impairment in their brain.

This often cause them to show various symptoms such as hearing things that are not there, falsely perceived their identity, etc.