Should I yell at a girl who showed off something I'm sensitive to?
If I may ask, is being sensitive easy or difficult? This will help me better understand the issue.
It easy to be sensitive but difficult to deal with somewhat.
Someone told you your secret and showed it off, but you are being way too concerned with it. Most people probably didn't even care to notice, so you are worrying for nothing. Be the bigger person and let bygones be bygones in order to function like a mature adult and not yell.
Too late, I'm already yelling at her.
Oh, I am too late then, but after you are done yelling, you should apologize and ask her if she understands why you had to yell at her. Maybe this will lead to a healthy discussion and rectify the issue so you both can go forwards with the friendship.