To be honest, from a philosophical point of view, you could argue that your whole life is one grand delusion, no matter the circumstances. Descartes, who is French, said "je pense donc je suis", I think therefore I am. In other words, every time you think, you prove your own existence. Unfortunately, you can only ever prove your own existence, not that of anyone else. So, in answer to your question, you don't know.