I could my husband fucking his sister. I was already suspicious something was going on between them. When he asked me if his sister could come and stay with us after she got separated from her fiancé. On this day I got home early from work and because I was already suspicious, I didn't make any noise when I got inside. I start recording with my phone and got some evidences before I let them know I was there watching them, but after I watched for awhile I got horny than hungry. I had mixed feelings about what I was watching, so I didn't reveal myself and decided to thing about it before I let them know that I knew. By the end I wanted to join them.