My mother blames me for her marriage falling apart. What should I do?

The story starts about ten years ago when my parents got a divorce. My mother wound up cheating on my father. She believed her new boyfriend would give her everything that she ever wanted such as a home in Hawaii and that she would never have to work again. She blamed it on my father drinking which was bull because he rarely drank. After my father moved out, her boyfriend moved in right away and she found out that he was not as rich as she thought he was. Soon thereafter, they broke up. She later met someone that made a very decent wage and they were to be married two years after dating. After she got married to the man that she is married to now, my mother and I fell further and further apart unlike the relationship between her and my older sister and younger brother. She forced me to support myself starting at the age of fifteen. I had a full time job and was also going to high school. I paid my own bills and never received any istance from her unlike my brother and sister who never worked and failed to maintain decent grades in school. My mother and I never talked after I realized that if I decided to quit working and focus solely on school, she would never help me regardless of the 200 a week my father was giving her in child support just for me. Later on I decided that I couldn't take it and I finally moved in with my father. Things were great with him and we still have a wonderful relationship. I moved back in with my mother a year later so that I could be closer to my friends. I started college and landed an amazing job. At that point I was looking for my own apartment and I thought things were going very well. My mother and I still weren't on speaking terms but we could tolerate each other. My job then started to go south, I was only working one day a week, trying to find another job and trying to stay in school so I could get my degree. Unfortunately, there was no way for me to pay for my bills so I asked my mother for some istance while things were a little rough for me. Her facial expression looked like I had tried to kill her. At that time she was still receiving child support for me. So from then on I decided that I needed to stay away from her while she worked on her own problems. I started living with friends a few nights a week and seldom went to her house. One night when I had to stay there because I had to work the next day after getting back to the house from work, I decided to thank her by cleaning the entire house. She came home and I asked her if she noticed how wonderful the house looked. She snapped back and said, "did you ever realize that I have been supporting you?" I didn't say a word and I left. It was two months until I talked to her again (this last Christmas). My boyfriend and I went to Christmas at her house and she hardly spoke to me. It felt like I was some homeless person that wasn't supposed to be there. She has a beautiful relationship with my brother and sister, laughing and joking around the entire time. When she looked at me, she seemed disappointed. After that, I moved into my fathers house again. A few days ago my boyfriend got a job roughly an hour away and very close to my mothers house. After he got off of work, we went to my mothers house and we asked her if we could catch up on some sleep before we had to start another big day. She gladly agreed and set us up in one of the spare rooms. We woke up and she and her husband were gone. We waited to leave because I wanted to say bye before we left. She came back, her husband went upstairs and she told me that she wanted to talk. The first thing she said was, "You are never allowed to stay here again, you are ruining my marriage." I was in shock and automatically defended myself. I had learned earlier that my step-father was saying horrible things about my brother, sister and me and my mom refused to stand up for any of us. I had also learned that she tried to entice my father to "get back together with her" which he quickly declined. I mentioned all of these to her and she never denied any of it. When she didn't I told her to stick up for her family and for herself because I know my step-father hates all of his step-children (only because his are so perfect). I don't know what to do. I have considered to shut my mom out of my life completely. She acts as if I am the devil and a home wrecker. I don't understand what I did and why she is saying some of the things she does. What should I do?