My family had known about my struggles for years so when I actually was diagnosed, it was a relief for them when I told them. To them, it meant a definite course of treatment and hope.

This is how a good friend approached her folks when she moved back home after living away for years and they did not know. Perhaps this will help:

She let them know she needed to talk to them and started out by discussing and pointing out her symptoms, "you may have seen this, this and this with me..." and led into getting how she was getting help for them with a physician and therapist, and then into her diagnosis. She handed them a print out of factual information about BP to read, later and so any preconceived notions about it could be disspelled. She told them she appreciated their support and if she needed help she would let them know, but at the time everything was under control with her, her doc, and T. She ended by asking if they had any questions.

More than likely, they have seen the symptoms and will be relieved about your getting help.

I really wish you the best in our 'coming out'.