Fear of a Different Sort of Loss

My oldest child was born out of wedlock before I married my husband. While I love this child, I am aware that, in creating her, I sinned. But I chose life (yay!) And, although things have not been easy and I would not suggest purposely going out and getting pregnant before marriage (or intercourse out of wedlock at all, for that matter), I have been blessed. But the story doesn't end there. I got married when my child was 3 and my husband and I have provided a stable, loving family life for her and for all of our kids. We returned to the Church shortly after our second child was born and have been practicing Catholics ever since. Her father has never paid any sort of support and has never taken care of her for more than a few hours at a time. He is still in the picture, but not in a legal sense and not when he has better things to do. Recently, he has wanted to play family with his girlfriend using our daughter. He has asked for visitation (whatever this means) and he wants our daughter to meet this girlfriend. Now, my first thought is that this isn't good for my daughter. She has a stable, loving home and family and it would not be good for her to live in a fractured sort of way- with one family here and another there. I am concerned about how she will feel about this woman and the fact that she will have to spend time with her. I am concerned about how this will effect our family unit as a whole and also us as individuals... she has a brother and sister, after all. I am also concerned about her being exposed to values that are not a part of our family's belief system and there is absolutely no way I will allow her to spend time at a house in which her "father" lives with his girlfriend. No way. You see, I have made many mistakes in my life and now my entire existence is now devoted to teaching my kids to live differently than I did. I don't want them to make the same mistakes and suffer as a result of these mistakes. I also came from a broken and "blended" home and so I know how much fun it is! Really, I know what feelings and issues may come from this and I am terrified! I am terrified of not having my little girl with me like she is now. I am terrified that this will rip our family apart. I am terrified that she will be led astray by the poor example sat by her father and his girlfriend and that any "bad" things she will learn will then be learned by the other kids. I feel like I am in danger of losing her and I am just not ready to lose another child! Sometimes I just want to ask God when enough will be enough... My stomach is in absolute knots! This is what sin does and this is how it affects generations! Sacred hear of Jesus, have mercy on us! Sacred Heart of Jesus, have mercy on us! Sacred Heart of Jesus, have mercy on us!