I guess it depends on what your family is like. You know them better than any of us so do what you think is right. I am just sorry to hear that you are in a situation in which you have to keep it under wraps. That in and of itself must nerve racking. My parents are very old school and when I applied for SSDI I did not tell them because, like you I didn't want to deal with thier reaction. A few months after I applied I was at my parents house and my Mother suggested I apply for SSDI. I was shocked but relieved. My parents finally accepted the fact that I could not work due to my psychological disorders. I wish you the best.