Hello and welcome,
I am sorry to hear of your girlfriend's depression and bipolar disorders.
Most bipolar people enjoy long periods of normal mood. If she continues treatment, she may never have another major mood episode. She will probably have hypomanias and depressions, but not as extreme as this mood episode.
Here are some suggested books for you to read, "Loving Someone with Bipolar" by Julie Fast. Bipolar for Dummies is pretty good. As is "An Unquiet Mind" which is written by a Professor of Psycholigist who has bipolar.
Also, don't treat her any differently than before, except no drugs or alcohol or staying up all night. All of these things can cause mood episodes.
A must is for you to take care of yourself.
Kindly,
Kitt
I am not a Doctor and there is NO substitute for getting proper medical diagnosis and advice.