Did I do something wrong?

I make jewelry. It's something I like to do and I sell it. My ex husband's step daughter's birthday was today. She will come over sometimes with my daughter and me and her talk. She's very smart for 11, so I made her a necklace for her birthday. I knew she was coming by because she would be by because my ex was picking our daughter up today. When they came to pick her up I gave my daughter the necklace to give to her step sister. Her step sister ended up coming inside crying to give me a hug. She said nobody told her happy birthday and her mom just spent all day yelling at her and didn't even acknowledge her birthday. I told her Happy birthday and sang a quick song to her and she smiled and went back to the car. A few hours later her mom came by my house and she told me never to give her daughter a present again and threw the necklace at me and told me to stay in my place because next time she will beat my ass. Be honest. Did I do something wrong? I was just trying to be nice