What are your opinions on this?

Okay, today in Social Studies, me and a friend, I'll call "Bridget" (protecting the innocent) were working together on a project, and two other girls, "Lauren" and "Emily" were working near my desk. My stuff that I wasn't using was on my desk. So when we had to clean up, long story short I ped by my stuff, which had some scraps on it that were not from my group, and picked up the scraps and chucked them. So Bridget was like "why would you pick up their trash?!" Acting like I gave government secrets away when I just picked up another group's trash, when I was in that area and so that they didn't have to. And I was like, "well it's on my stuff!" Or something like that. And I was like "Everything I do, I get yelled at! What do you think that does to my self esteem?!" I mean, I really feel that EVERYTHING I do, someone has a problem with it! And as a result I feel like I can't do anything right. And Bridget said "I don't want to hear it!" I was mad but before I could say anything more the teacher had us simmer down. I mean really. I may be being biased, but all I did was pick up another group's trash, and it wasn't like I wasn't gonna pick up our group's trash, I was just helping out another group. It's not like our grade could drop if I helped out another person!! What do you think? Maybe I over-reacted a bit but I think she did too. Your opinion?