Brother-in-law Pair Bonds With Me

When I was nineteen I went to an off campus party, A guy picked me up and took me to his place. After going from hole to hole he finished in my ass. He took me to his sister's room and told her to look after me because I moved too much. From that day until today I live with her, she shepherd me through college while she was going through vet school. We are now 26 and 29.

From time to time her brother comes by to pair bond with me, that's sex to you and me. Sometimes she is looking after me, and sometimes she refers to me as her SO. I consider her my SO, I consider him someone I can't turn my back on. I am not sure who I am.