I'm soo annoyed at my mother! help me!?

my mom is a very controlling person. I made a new friend she doesn't really approve of and she told me that she could call my landlady at any time and if im not at home i will be in really big trouble. I live in an apartment away from home. I did not think she was serious about it. But just now, she just called my landlady to inquire about me and started yelling at me too! OMG i can't believe she would stoop this low to make sure i'm studying! It's like she doesn't trust me at all! I'm almost 19 years old, and have 3.81 GPA. I've given her no reason to doubt me. I'm fuming right now! What do i do?!?! I'm soo pissed at her!