I agree with Sleeps and Rhapsody,
Once you have told long time friends and/or partner, and you find them becoming distant, they aren't worth having.
What one can do to help them understand is to educate them about your illness, and mental illness in general.
There are some good websites, or you can even get pamphlets usually found in pdoc's waiting rooms, there are many sources you can use. So often there are people oblivious or in denial about the growing population that have some kind(s) of mental disorder(s). There are so many commercials and advertisments found in so many magazines about mental illness and medications now being used, this is due to the increasing knowledge of mental illness and treatments.
It is hard for me to believe that someone hasn't heard about all of this by now, unless they have locked themselves into some form of isolation from the world around them.
I personally feel that after someone learning about mental illness and then still do not want to stay with a friend or partner, is really not worth calling a friend. On the other hand, if someone has been episodic around them, it can make it more difficult to understand. If someone has had violent episodes, this can scare off friends, due to feeling awkward or threatened is something I would understand and then wouldn't hold it against them if they do decide to leave. There is just so much others can and should have to put up with. It is always a comfort though, if they want to stay, learn and help their friend or partner dealing with their disorder.
It also can become frustrating for them, if a patient refuses to follow their med regimen and treatment, there I can't blame them from distancing.
Sorry for the rambling, the most important thing to do is wait and see how they view mental illness, any chance you get to help them learn about it, may help prepare them for if and when you want to tell them.
I wouldn't tell anyone that is new to me,you do not have to, but do not ever feel badly about yourself, you haven't committed some sort of sin, it is an illness/disorder, just as diabetes, heart disease,high blood pressure, etc. things that require treatment(s).
I wish you lots of luck with this, and with your own health.
Please take care now,
DE