My parents are very homophobic?

My birthday is on July 20th and I am having a Sweet 15 because next year I will be in Germany for a month visiting my dad's family so I'm having my big party this year and I've already planned. My friends who are girls and I will go to a day spa and get a pedicure, manicure, get our hair done, and we will get massages. After, we will go dress shopping and a limo will pick us up and take us to the city where my parents rented a ballroom at a very nice hotel. The guys will meet us there but only the girls will stay at the hotel. However, I was making invitations and writing a guest list for about one hundred people and I talked about the people who will be coming with my parents and one of my closet friends is a guy and he is gay. He acts very gay with his voice and hand motions and dresses very stylish and Feminine but he is still fun to be around but my parents say he is not allowed to come because he is gay. I asked why and they said that I should know and that is their only response and I got so angry and got into an argument with them. They are being so mean and now are saying I will not have any party because I wanted to invite a queer! Any advice on what I should do?