Bipolar disorder or plain evil?

Hello
Recently a friend of mine has been diagnosed with bipolar disorder, not type 1 nor 2, something called “bipolar spectre”, she was basically told that she has “higher” days without experiencing the full blown manic side, and has depressive days, which are pretty heavy.
Now, I’ve met this person for about 6 yrs now, the thing is I recently found out that she talks really bad, nasty stuff about me, pretty much everything I know about her it’s been a big lie, she’s just very very manipulative. What is this? are bipolar people like this?? do they tend to lie to get attention?? or this is just pure crap? How do I relate to her from now on? Plus, she “copies” everything I do (clothing, musical tastes, even seems to fancy my boyfriend).. is this normal?
Plus, we work together, since we’re lawyers and started a firm together with another friend. So, are we doomed?

Thank you
And please, I don´t mean to harm or offend anyone with this condition, im just kinda mad and not really understanding anything about this “friend”.