Family involvement in relationships

My family is way too involved in my relationships. I think that this is partly my own fault because I talk about who I am seeing all the time. If I don’t they will ask me! They are pretty judgemental and have the ability to persuade to think like them.They have such a strong influence on me that I am constantly thinking about what they would say or do even though I should be thinking for myself. Because of this I am unable to make decisions independently without second guessing myself constantly. I am 26 going on 27 and I live with my sis and her husband, even if I want to stay out for the night I have to let them know and then I get bombarded with questions the next day about it. I have to live there because I am still in school and cannot afford to live out on my own. I really don’t know how to handle this situation because if I don’t say anything they will ask. Please help me live my life without worrying about what my family thinks all the time!