23 years old, engaged, and wanting my own life

I am 23 and recently got engaged. Let me tell you a little about myself. I have lived with my aunt, uncle, cousin, since the age of 8 when my mom died. I met my fiancee in high school and we’ve been together since. In my house I am like a real live cinderella and always have done what everyone else has wanted for so long I feel I can’t make a decision I want because of the judging and bashing I would recieve. I’ve lived the way my aunt and grandma has wanted me to. As I got older I did everything right while my cousin got into everything not so right.My aunt ould always say things about my relationship, when she did not have a single clue about it. she would say things like “your boyfriend is never going to marry you” Now I feel I have proven her wrong. My fiancee wants me to move in with him and I would like to. I want to start my own life. I am afraid to tell them, because they will retaliate and not help me with my wedding. I have lived my life by doing everything they wanted, now I feel I can’t do things I want because they will bash me. I’m so tired of having to do it all, I run all the errands, clean the whole house from top to bottom while everyone sits around not helping(mind you it’s all adults). I was really mad becasue I went out of town for my birthday( which is when I got engaged), well when I returned home I came back to a dirty kitchen, a list of things to do that could have been done, and an overall filthy house. I am really sick and tired living for them and not myself. please give me advice on how to tell them I am leaving.