School drama

So basically there's this girl (let's call her A) in my class and she's kinda smelly but no one ever tried to tell her because we didn't want to hurt her feelings. 

Yesterday my classmates were talking to their religion teacher (we're divided in groups) and they complained about the smell. The teacher said she wouldn't be the one to tell her and that it'd be better if it was one of us. They asked her how to tell A without hurting her feelings. Anyway, not even 30 minutes later, she walks into our classroom and asks A to go with her. After they were done talking she walked back to class and didn't look anyone in the eyes. She looked so hurt and I understand why. I mean how would you feel after finding out everyone's been talking about the way you smell, especially to a teacher. 

Today she didn't really talk to anyone. I could tell she was ashamed and also mad at us.

How should we fix thisss if our headteacher finds out we're f*ed.