Your friend is ignorant of this illness and perhaps you can educate them.
Go into Fibro 101 and print out the link called Doctors Respond to New York Times Article. It speaks volumes about this illness that is, by the way, recognized by the American Medical Association, the American College of Rheumatology, the World Health Organization, and the National Institute of Health, to name a few.
Also print out the link called A Thorough Explanation of Fibromyalgia and see if these articles will educate your friend. If not, make the discussion of fibromyalgia "off limits."
By the way, stress can make your pain worse but it isn't the cause of the pain. Right now they think this is a neurological problem dealing with nerve endings and how we interpret our pain. Our pain is very real and it's not psychosomatic.
Sherrine