Why did they do all of this to me?

What did I do wrong??

I'm crying quietly in my room, not wanting my parents or my sister know that i'm crying

Again, I check their chats from my cellphone, 

"That stupid b*t*h, lucky her. She Is rich, smart, and pretty. If don't, I will just throw her since long time ago."

I can't believe this, my very own bestfriends talk about me behind my back

I don't know what to do now.. I trust them very much, And I don't have anyone else beside them. And now I know that they are just using me. Asking me to do their homework, asking me to buy this and that, and they even asking me to drive them home. What the are they thinking? I'm not their maid, I'm not a robot. . I don't know what to say anymore. I just feel like I'm going to puke my today breakfast out today. "_____, Can you come out dear?" My mom is calling me from outside the room, she knicked the door several times. "Okay, mom. I'll be right there in a second !" I replied. My voice is trembling since I was crying for pretty long time. "Honey, are you okay? It's okay if you don't want to get out. I will tell him" my mom said worrily, okay.. so, i don't have to get out right? And him? Who is him?? 

I quickly run and open the door, my can hear that my mom gasped "Honey.. Why are you crying? Tell me.." She said as she pull me into her warm embrace. Maybe this is one of the reasons why did my dad marry her. You cannot resist her. Especially her warm hug and her soft motherly soothing voice."My friends.. Th-they are talking bad things about me behind my back. I don't know what did I do wrong. You know, I just realized, afterall this time, they treated me like I am a servant, a robot that have to do this and that for them. And this is what they give to me?" I started to sobs quietly again. "No honey, don't ever call them your friends anymore. They are back-stabbers. They don't deserve a good girl like you to be their friend." My mom caressing my back as she whispers every words she said. Still loud enough for me to hear those words.

"B-but Mom, I don't have any other friends in school. They are the school's popular girls. Everyone will be their friends and everyone will hate me!" I said fastly, and of course,not so clear. But my mom understands every words that came up from my mouth and release