Hi, Tiger

I am sorry that you are left feeling so bad by your friend. It isn't quite so easy to explain all of this but I will give it a try.

I have a daughter who was recently diagnosed as Bipolar and has I am sure confused her good friends as your friend has seemed to do to you.
It sounds to me as if you are in your late teens or early twenties. My daughter is 15 and a sophomore in High School. IN the past few years she went through self harm, depression, ran away from home, shoplifted, attempted suicide and was hospitalized 4 times in an effort to figure out what was wrong. During this time she also became hypersexual and participated in things that were risky or self destructive. Her friends were so upset by this and wanted the old Erin back. However, Bipolar took over and alot of what she does or the way she acts is very much controlled by that.
She is on meds now and things are alot better. But still she says hurtful things and can be upset with friends at the drop of a hat. This has alot to do with how the disorder affects you. The part of the brain which controls thought processes and emotions is affected. That is why often a person who has Bipolar will do things impulsively without giving much thought to the consequences. That is where the risky behavior comes from, the self harm, the hurtful words, anger, irritability, frustration and what we call the "mission mode". That is, they want what they want and have to have it right away and don't care how they get it or who they hurt along the way. Sometimes it means avoiding friends that stand in the way of getting what they want as well.
The meds help to some extent but it takes alot of self awareness on the part of the one who has Bipolar as well to help them through all of this. Often without this the things they say or do often affect their friendships and relationships as you are beginnning to see.
My daughter has been lucky enough to have a close group of friends who really do care about her. She at times thinks that they are out to ruin her life when all that they are doing is trying to help. Often I am sure that they feel much the same way as you do because of how she sometimes perceives things to be that really isn't the case. And alot of the time when you are trying to help you are standing in the way of what their mind is telling them that they want to do.
What I am saying is, that it sound as if your friend still needs to be stabilized on her meds and work on developing techniques in which she can identify her behavior and feelings and work through them so that she doesn't hurt her friends or herself. This takes time and it really takes a special friend to be able to support somebody through this. You may better understand what your friend is experiencing by reading as much as you can about Bipolar, what it is and how somebody is affected and what things you can do to support them. By doing so you may be able to understand that the things that your friend is saying and doing ARE very much a part of this disorder but she must also realize that there will be consequences to her behavior one of which may be losing a very good friend. Setting boundaries of what you will and will not tolerate from her may be part of helping her out. And also understanding more about her disorder and ways you can best support her may be necessary as well.
You sound like a wonderful friend and your friend really could use a friend who will look out for her and understand how difficult this disorder can be.
I hope this helps you better understand that most of what you are seeing is due to the disorder. And that in time with the proper meds, therapy, and support your friend could lead a fairly normal life.
Good luck and feel free to ask anything that you think may be of help for you or your friend.
~ Goody