It is unbelievably complex and though there are commom symptoms between folk, there are differences. I have a very close friend who also suffers "normal" depression on top....just to add some cream to the mental cake.
She has been sectioned 6 times, once in France.......I have witnessed it but once and it was not very funny. She has been on lithium too, but if you lose 'control' its like an earthquake going off - the chock and then the major tremors; you can't just bring it back into the normal emotional tunnel.
K is a very caring person overtly, and a very good friend; she knows all about me and I her...things only very, very good friends share, - her sex like, mine (and remember this is female to male)....however, when she 'ascends' (which in many ways is even worse) or 'descends' out of the normal 'tunnel' that we exist in emotionally, then all hell breaks loose. It is very frightening how the dark side of the brain can take over and the way it works in scenarios based on some semblance of reality......but completely turned through 270 degrees and then turned again to come up with the most perverted (not necessarily sexual but sometimes) scenarios....
K's husband has been a complete saint - the patience needed when your mother is accused of knocking off an Indian boatman......just one 'very small' example.
It is very frightening for the uninitiated - you have to realise that this is not your friend or relative that is talking, it is a very dark spirit......they will lose friends and relatives as some of the vitriol is so aggressive and invasive........it takes courage to stick with the,.
Yes, there is a gradation of selfishness, but if she is suffering you need to take/search out necessary professional help be it her family, her managers, whoever......you are her friend - stick with her. They need help - but you need a lot of balls to be able to do it and rationalise some of the 'hatred'