Help..

Soooo for 4 long years I have taken my partner back and forth.. from cheating on me multiple times ... to lying ... u name it .. the first 6 months of our relationship she slept with her ex behind my back when I went away for a week.. and hang out with her ex.
She's done a lot of hurtful things to me over the past since 2013..
Back in the day I used to write my feelings down and things she did to hurt me ..
Well.. she went through my stuff when I was at work and read my diary .. and she hinted a few things throughout the weeks .. only today we had a big fight and she threw it in my face .. and made me feel like it's all my fault .. 
I really don't know what to do.. I feel angry and hurt at the things she also said today. Basically blames everything on me .. she got very violent in the car and slammed her breaks on and kicked me out and then skidded away.. and then came back and said to get in the car and when we get home she's grabbing her shit and never speaking to me ever again. So I'm hyperventilating as all day she has spoken to me like shit.. 
and then when we get home she tries to cuddle me and kiss me .. after being horrible..
About 8 weeks ago she lied about going out clubbing and told me she got back home by 11 as she only went out for dinner with her friends ( since apprently I couldn't go ) 
But a few days later someone told me they saw her out and then she was busted .. 
that is another story.
I feel like I am stuck in this relationship.. I feel like I'm so depressed and upset .. but I jus can't break away without it being so chaotic ... and drama and things get thrown around and it's hurtful.
I need help.. I'm driving around and all I can think about is bashing into a pole.