bipolar disorder and hitting

I really need some help here. I have been dating the same girl now for almost 2 years. Our relationship has been so wonderful and perfect and on the other hand so so awful.

I don't know what is right and wrong in this relationship anymore because she is bipolar. I don't want to hold things against her when she has no control over herself. But, I don't really know if she has control or not.

Recently she started getting really jealous of everything and everyone. Im a coach and teacher. My job takes a lot of my time. She is so mad that I am not there whenever she needs me that she threatens me with leaving because I can't fill her needs. But, she has this way of manipulating things to make me think it really is my fault when I know it isn't. She finally got so mad at me for walking away from her hostility that she hit me very hard in the back. Needless to say, I can't lift my arm without hurting from the pinched nerve it caused. Is this from her being bipolar? Is this common?

I am a very patient person and will do whatever it takes to make things work. She is going to the psychiatrist this week because I wanted her to. Things just seem to be getting worse since she agreed to go. Is that ok? Am I supposed to wait for her and give her that chance to "get better"? Or is this too toxic to stay with?

Please Help.