AITA for not attending my daughters wedding after she said I was not allowed to bring my step daughter?

I'm a 52 year old father who was married to my ex wife from 1996-2005. We have one daughter together, Emma, who's 23. In 2006 I got remarried to my current wife. She was a single mother to a little girl named Isabella, who was 4 years old at the time. I've always raised Isabella as if she was my own because her biological father refused to be apart of her life and never paid a penny in child support. I've always loved Isabella like my own daughter and she would address me as her dad. My ex wife has always had a hatred for my new family and would try to create division and animosity between us. <br><br>Last year my daughter got engaged and I was planning on walking her down the aisle. A few months ago we discussed wedding details and I wanted to make sure that I could bring my family, including Isabella. She said that it would be inappropriate for Isabella to be there and that it's "a day for parents and their biological children only". I tried to explain that Isabella is my daughter and that I've been there for her since she was four years old but she said that it's not the same and she didn't consider Isabella her "real sister". I argued it's not fair to exclude my wife and other daughter because they're family and it's "a day for family". I told her that if Isabella isn't welcome to come then I'm not coming at all because I refuse to abandon my daughter on her sisters wedding day. She said fine and that I was being ridiculous. <br><br>She got married last weekend and I did not attend. She has blocked my number and my wife's number. I just want to know if I did the right thing by standing up for Isabella?