Hello and welcome. Lets try and look at what you are dealing with bit by bit, and ill let you know to the best of my ability what is going on in her bipolar mind.
You said no matter what you do she always blames you. That is definetly hypomanic behavior. When i was hypomanic and out of control i also blamed everything on my wife. It was her fault that i had affairs because she didnt have sex with me enough. Doesnt make sense now but at the time it made perfect sense.
The thing that is tough to understand about Bipolar is that it doesnt just happen over night. It is very sneaky and it creeps up on you over the course of years and gradually changes how you see the world. In her mind she is perfectly fine and you are the one who has ruined her life. In the end only medications can hope to get her back to normal. However,and this is the big one, she has to admit she is the one with a problem. I had a moment of clarity after the worst night of my life, this moment of clarity has allowed me the vision to see that it was ME who had a problem, not my wife.
In the end unless she is willing to accept help and medications and therpay than she has very little hope of coming out of this. BP gets worse with age so she isnt going to get better in a few months. It might just take walkign away because at this point you have to consider your own health, emotional, mental, and physical. Its good you ahve been getting therpay, it will help you along. It may help to think of it as grief coulsing, BP has taken your wife from you just as if it was cancer.
In the end i would definetly put some work into thinking about what you are willing to accept and what you cant. Once you get that figured out than you can move on and make the hard decisions that will guide your life.
Hope this helps. .