All I can say is, don't stay hooked on someone who is not reliable in life, get in the here and now and celebrate what you've got (which is freedom from someone who has bipolar disorder). If it helps, you should also remember that you don't know what goes on in her present relationship(s), you certainly don't know that she 'treats really nice' any guy she dates. It's more logical to assume that she treats everyone she meets just about the same way she treated you. The reason I said "if it helps" about thinking this, is that you really shouldn't be thinking about her at all, except to say "Thank you, God," that you don't have to be her boyfriend any more. Buck up and count yourself lucky.
Yes I have been in therapy and my counselor asked me why did you stay in this so long? He asked me as a kid did I have a sick friend or is it because I am a firefighter and enjoy helping others? He said the old saying a leopard does not change its spots and that I should consider myself lucky because if I did end up getting married I would be in for a life of misery and she would take everything I have and not have thought twice about it. Thanks for the advice I appreciate you very much.
Jim
It's kind of hard to understand why you put up with any of this, much less why your reaction now is to have hurt feelings and wonder why she apparently treats someone else nicely and didn't treat you nicely, unless she is very like some important female in your life when you were a little boy who had the same pattern (and to whom you also reacted like a sad, wishful puppy). I'd suggest going in for some counseling. A person who is not hooked by all the kinds of games she was playing would have just told her goodbye after the first stunt she pulled, and would have been indignant that they were being played. Why did you let her manipulate you? That's the question to work on with a counselor.