Yikes! That sounds rough. I can empathize with you.
You can't force them to understand. but perhaps someone who knows a lot on this disorder can take them aside and inform them? Or maybe if they are the kind that would read up on facts then maybe pursue showing them those.
No matter what, what you feel and think is real. Just because it may not be accurate does not mean that it isn't real! (I hope that makes sense on how i'm meaning it).