Frustrated

Ok, so i am really frustrated and not quite sure what to do. First, my sister and my friend went on a trip this weekend and didn;t ask me to go. I was hurt by this alot. I'm told i'm being immature and a bunch of other crap. Well, my niece was saying she understood how i felt and was being sweet to me about the whole thing. Well, it turned out that, that was short lived. She constantly has been texting me and asking me all theses questions and i give her the short answers. I told my friend we were not friends anymore b/c she lied to me. Well, my niece keeps asking if i am friends still with my friend and all i said was no b/c she lied to me and that's something i don't stand for. She took that and told her mom, and also told her mom i was venting to her and a bunch of other crap that was totally not true and my sister texts me and says i need to stop and all this.

Hello, i didn't do anything. My niece is an instigator and likes getting people in trouble. Then, later on tonight, we had an event at church. Well, i ignored her the whole evening b/c i am upset at her for running her mouth and telling lies. I spoke to her once the whole evening and she calls her mom again and says things about me that are totally untrue. Well, then my sister text me and says can't you act like an adult and just ignore her. Um, what do you think i've been doing all night. I have 6 people who can attest to that fact. I then proceded to call my sister and tell her that i have ignored her all night but she keeps texting me and everything. Its a frickin soap opera and i'm sick of it.

She's my niece and i love her bur i'm sick of her always running her mouth and saying things that aren't true. She's 13 and i know its an awkward stage for her, but its frustrating and i don't know how to handle her anymore. Any advice is appreciated.