I got married last year and recently found out my step-sister who was also one of my bridesmates has been having an affair with her uncle by marriage. We are semi-close, but I noticed a change in her behavior before the wedding. I shrugged it off thinking she's just a single mom trying to make ends meet and was just tired or whatever (and I don't like to pry). But to make matters more uncomfortable she's now PG by him. When I asked her who the father is she changed the subject real quick. The whole family knows now as she and the uncle don't deny it and she's pretty far into her pregnancy. I'm shocked and saddened, I thought I selected someone as a bridesmate as somebody I could count on as a woman and individual, but she turned out to be somebody I can't trust. I'm not angry at her, I'm just in disbelief and don't know what to say to her now.