[FULL] Birthday Party Woes: Stepmom Out, Drama In

Daughter doesn't like her stepmom and asked me not to invite her stepmom to her birthday party. Now I'm accused of trying to destroy their family. I, 32 female, divorced my ex-husband, 36 male, six years ago when our daughter, 9 female, was 3. He came to me one day and confessed that he had fallen in love with one of his co-workers, who I'll call Melissa, and wanted to chase what he felt in his heart. He got me married and now they have a son, 6 years old, who is the half brother to my daughter. My daughter's birthday is in 9 days. I was going over things for her birthday with her, like the theme and the cake, but when we were going through the guests list, she looked anxious. When I asked what was wrong, she told me that she didn't want to invite Melissa. I asked her why and she explained to me that Melissa would make weird comments sometimes around other parents or to her. For example, when Melissa would pick her up from her dance lesson, she would hear her say things like, that's why I prefer boys, girls only like pink and tutus, calling her a brat, and other things. She also told me that every time her half brother would do something to annoy her, like breaking her toys, calling her names, starting a fight, etc., Melissa would always defend her son and punish my daughter every time, saying, boys will be boys, or something along those lines. I asked about her dad and she said that Melissa does that even when her dad is around, because he's always in his office, so it's like a free pass. Later on, I called her father. He asked for the date of the party, since her real birthday lands on a school day, and I told him that his wife was not invited. I think it was on loudspeaker because I heard Melissa screaming at me, claiming that I'm trying to destroy her family. I promptly stated that I would be open to speaking more about the matter in a private setting and hung up. Am I wrong for not inviting my ex-husband's wife to my daughter's birthday party because she told me not to? We have a 50-50 custody agreement. My daughter explained to me that she never told her dad that she didn't want to invite her stepmother because she was scared of ruining her father's marriage, because, well, he seems happy. So, a lot happened. First of all, I met my ex for lunch alone. I explained everything that my daughter told me. At first, he was defensive and told me that she was overreacting. I replied that even if that were true, his relationship with his daughter is at risk. I gave him a choice, fix the problem, or I go back to court for more custody. On Friday, when I came to pick up my daughter at his house, I talked to her in private. She told me that her dad spent a lot of time with her that day. He picked her up from school and dance class, helped her with homework, and played games with her. Melissa then told me that she accepts not going to the party, but still wanted to see my daughter blow out her candles for her birthday. She baked a cake and asked my daughter if she was okay with doing it before leaving. She seemed okay with it, so all of us gathered around the cake. When my daughter blew out the candles, her half-brother decided that the good thing to do would be to smash my daughter's face into the cake. To be honest, if this were not a kid, I would be in prison. He and Melissa burst out laughing while my daughter was crying. Melissa then told her that she was being dramatic and emotional. We got into a heated argument, and to my surprise, my ex-husband was on my side, saying that it was not okay. While arguing, I noticed that my daughter was not there, so I left to check on her. I helped her clean herself, and then we left for my house. I tried to cheer her up, but she was still a little sad. The party went well. Her dad came, and during the party, I told him that I want more custody because of his So, yeah. I will update you if anything happens. Some of you asked questions about my daughter's reaction. My daughter is really shy, and she's a silent kid, except for me and her dad. She does not talk unless spoken to or if you bring up a subject that she likes. When something upsets her, she just stays silent and cries. It's always been like that, and it is what she did. She was crying the entire ride back and went to her room as soon as we got home. My ex-husband apologized for his wife and son's behavior at the party and told me he would fix it, but he also asked me not to fight for more custody.