My 16 year old daughter Megan just finished her cancer treatment and she's lost her hair in the process and she's been incredibly insecure because of it. She no longer meets friends nor welcomes that at her home or even meets family in person. It's been bad to say the least, but her stepbrother Ben has been making it worse with his nagging comments and jokes about her looks. He tries taking and posting pics of her secretly to share, but I shut that down even though my wife thought it was just harmless teasing. My wife's sister's wedding was last week. The family wanted Megan to go, but she didn't want to. I spent so much time trying to help her and convince her to start socializing again and see family. She agreed under the condition that I let her wear a wig, which I agreed. Not only that, but I took her shopping to pick her own wig and she looked beautiful and stunning in her pixie hairstyle wig. My wife and Ben laughed when they saw it. I don't know why. We went to the wedding and everything was going well until this happened. We were all sitting and we started talking about Megan's looks. Suddenly Ben reached out and pulled her wig and exposed her head. I was shocked and I froze, but Megan yelled and took her wig and ran. Ben, his cousins, and some guests started laughing. I was upset, especially when I looked over my shoulder and saw my wife sitting next to his mom, her mom, and laughing. I lost it on Ben and braided him in front of everyone and took my stuff, got Megan and got into the car and went home. Ben and my wife didn't have a ride home and my wife kept calling me and I didn't respond. She came home asking about me leaving mid-wedding and upsetting her sister and then leaving him and Ben with no way home. I argued with her about how Ben embarrassed Megan and humiliated her publicly, which must have ruined what's left of her self-esteem. She said that it was just kids teasing each other and that I overreacted and Ben had no malicious intent. He was just messing with her. I was sick of it, but she said that this was their way of bonding and step-siblings and I was getting in the way and being over-protective and unreasonable. We didn't talk to her about that and Ben is refusing to apologize and his mother is backing him up.