Are you gay?

Last year a person in my grade who used to be unpopular( like me), now is popular. They were dared by someone to ask me out as a joke. I assumed that’s what it was, and said no,they then said, “why did you say no, is it because your gay or something”, after that I didn’t really respond, because I am gay and haven’t come out. But after he asked me that he prodded more saying stuff like,”will you go out with her”, and more along those lines. He then started telling people that I was gay. I mean, I know it’s not the worst insult, but it really made me so embarrassed, and sad. Just seeing how people reacted to his joke.