My life's secret.

My sister and I have had a sexual relationship since the beginning of highschool. Our household wasn't great but we found peace with each other. We spent a lot of time at a friends house. He and his parents were great. Though after sometime there my sister caught his dad fucking me in the ass. She in her anger said she would eat us out if we both didn't fuck her... So we did. Before we stopped associating with our friend and his family. He, his father and I had all taken turns with my sister, many times all together. Shit part is even though I par took in it, it burned a hole inside me because I love my sister and it aggravates me seeing her fuck our friend and his dad. Anyways, yeah. Now it's back to just her and I, though I think she often thinks of those events while we have sex.