Hi Allison, and welcome

Is the person in a safe place? Making sure that both they and you are safe should be the first priority. Other than that, I'm not sure that you will have a whole lot of luck if you're trying to talk them out of their delusions... my opinion is that you should probably enlist a psychologist with experience in psychosis rather than try this yourself.

But, we have a few members here who experience psychosis, so why don't you also post your question in "Schizophrenia and Psychosis" and see if they have any advice for you from their perspective.

I'm sorry about your friend -- it must be stressful for both you and him.