I have a very complicated family situation. I wish to invite people close to me and whom I like. My father threatened to not come if I don't invite his mistress/girlfriend (he cheated on my stepmom with her and is now divorced and has a child with her). I really want my father to come but this complicates seating of my stepmom and my mother. Plus I don't even like my father's girlfriend. How do I handle this. I'm afraid there will be drama at the wedding and I'll have to kick them out. I would like to not damage the relationship with my father as he means a lot to me. Any Advice PLEASE?