How do I leave the man I love?

Me and my man have been together for almost 2 yrs. We've been through a hell of a lot! I love him to death and have always done everything I could for him. I know he loves me. All his friends say he does and sometimes he really does show it... However, he was not raised right and he treats me very bad at times. I had a talk with him a few days ago explaining that I felt we were going nowhere and that I was sick of fighting and wanted to work it out. He responded very well (at the time) and we discussed some very good plans for avoiding arguments. Well guess what? This mornign we got in a fight and he was cussing at me as usual. I reminded him about what we discussed and all he could say was "oh well, too bad". He will never change. I want to leave him but am so afraid of being alone. How can I prepare for the heartache? Any advice on how to approach this? I know Keeping busy is key, but any specific things that work for you?