My sister's ex
So about a year and a half ago my younger sister "Allie" was in her first relationship with a guy named "Sam" who was one of my close friends. Sam is one year younger than me and one year older than Allie. They dated for a little less than two months and then Sam decided to end it. Allie has issues with depression and managing her emotions, and threatened to kill herself over this. During this time, Sam and I became closer friends, eventually developing into "talk-on-the-phone-for-hours-every-night" best friends. I also suffer from some depression, and I am not sure if I would have made it through last winter without him. Over the past couple of weeks now we have been romantically involved with each other. Allie knows that Sam and I are close friends, but she has no idea how close. My family is moving out of state later this month, but I am staying in my home state to finish my senior year. Is this "normal"? Am I a bad big sister?