Growing up, I was always close with my sister because I spent a lot of time with her and told her everything. As I grew older and went to college, I began spending less time with her and our relationship went through peaks and valleys. About six months ago, I moved in with my sister and her husband (they live close to my university and I have one more year to complete) in order to save money which I was very grateful for. When I spend a lot of time with my sister and her husband and their friends, things are great. She is really nice and loving and fun to be around. Her friends and I don't have much in common so I prefer to spend time with my own but I will on occasion hang out with them.
Even though I live with my sister, I'm rarely home. I work full time for an engineering company during the summer, I have a boyfriend, I also work in a lab, and I like to hang out with my friends a couple evenings a week since I can in the summer. My sister does not understand this at all. She gets very upset with me when I'm not home frequently. She will call and talk about me to my parents and other siblings and treat me with a very cold attitude when I do come home. If I don't hang out with her friends she gets upset too. If she calls me that night and I don't come home to spend time with her and her friends because of a previous commitment, she will be angry when I see her again. This gives me anxiety to even see her or come home to the place I live.
How can I have a reasonable and calm conversation to explain to my sister that I love her but cannot deal with the way she is handling our situation?
We are both in our twenties living in the United States.