Friend of Mine long

First, let me say that I didn't know where to post this.

All names are changed in this

A good friend of mine (Carly) told me that another friend of mine (Lexis) was talking about me behind my back.

Saying how I was annoying, careless, talked too much and other things.

And I will admit that I am all of these things.

Careless, because I spent so much of my life carrying what everyone thought about me, and what was going to happen next, and the fact that I'm a teenager also plays a roll in this.

Annoying: I manage to be a follower, and I'm mean for no reason at all towards people, I tend to block them out when things get personal for my liking

I don't know what to do in this situation, I want to bring it up to Lexis but I don't know how with out seeming rude.