I feel so violated

I'm 17 years old. I have a boyfriend and we were dirty talking on Facebook messenger but nothing over the top mainly jokes. We are both still virgins. I left my laptop out on the table in the dining room (where my brother also sits at his laptop) and I guess I forgot to logout of Facebook because my mom said she wanted to have a talk with me then asked about the messages between my boyfriend and I. She said she read all of our conversations and so did my older brother and his girlfriend. I was mortified. My brothers girlfriend and my brother started making fun of me.