Gluttony. So embarrassing, how will I ever go back?

I am Catholic and I am going to classes at my church for my confirmation. My group was on the subject of the seven deadly sins. We came to gluttony and the woman who was proctoring us turns to me and says you probably suffer from gluttony, and then she fixes herself saying it is probably heredity. She immediately recognized her mistake and let out a little laugh, she didn't even apologize. I'm not saying that I'm not overweight because I am, I am about thirty pounds overweight. I looked around in our group and saw that everyone was snickering and trying not to laugh. I felt so embarrassed. I also go to school with most of these people. How will I ever face the courage to go back there next week? When I walk the halls in school and I see a person that was in my group I hang my head in embarrassment, hoping they don't notice. I'm so embarrassed. What do I do?