Son's dad embarrassed of him

My son is 16 and he is such a sweet kid. He is on the spectrum, but also he's extremely flamboyant and kind of feminine. Little fruity. Honestly he's always been that way and always something we knew. It didn't matter if you gave him a truck. He wanted to play princess with the other girls and would have tantrums when he wasn't allowed to and would refuse to play with anything. He's been this was since he was like 3. My ex husband has never really liked that. He's also a theater kid. We all went trick or treating. My older kids made their costumes and I took my younger ones to buy there's. My ex husband was there because we still try to do things as a family. I honestly still don't know exactly what my son was supposed to be. Just know he had on those combat boots that are healed and something that looked like a skirt. When we were trick or treating we saw some people dressed as stitch from Lilo and stitch and Ursala. My son said "Hi stitch!" She waved back and then said to Ursala "You give Ariel her voice back right now." They laughed and the girls daughter was Ariel and she said she has her voice and has been singing with it. My son said he can sing and his inner theater kid came out and people around us were laughing but not in a mean way. They all clapped. My ex husband smacked our son across the head. I yelled at him asking why he would do that and he said because he's drawing attention to himself while looking and acting like a "queer". I told him he's not hitting our kids and told him we were trick or treat without him. But it had already ruined it for all our kids because my younger kids especially my youngest daughter adores her older brother. They all adore him so seeing dad hit him not only upset my son but all his siblings. Everyone was having a great time.. Everyone enjoyed him. I think it's so sad he got mad because he was embarrassed.