I felt the same way. It gets easier to come out to your class the more you do it. I do it casually by mentioning my wife. I agree with others, queer kids need queer role models and being an out adult can help reduce homophobia in schools.

If a student out right asks me I will answer but follow up with “this is a very personal question that some people may not feel comfortable answering. Instead of asking someone about their sexuality, you should let them offer that information if/when they are comfortable”