I help and advice... My ex wants his fiancé to attend DS's student lead conference. This will be the first school conference that my ex has attended in 5 years. I have spoken with DS and he has voiced that he doesn't want his dads fiancé there. I have not told my DS that I don't feel comfortable with her being there either. I have asked the school if they will do separate conferences, but they will not since it is student lead. I know that the fiancé wants what she feels is best for my DS, but she and the ex have crossed many boundaries with me and we all have only been on cordial speaking terms in the last 4 months. She doesn't have a filter and doesn't know when just to be an observer. She says all the time "I'm not here to replace you and I want to be his Mimi/ other mom". How do I politely tell my ex that I don't want the fiancé there?