What's Wrong With Me?

I've just felt really crappy lately. I'm tired all of the time and shutting out all of the people I care (or think I care) about. I have no reason to feel this way. School's going great, I've made some cool new friends, and I'm not as stressed out as I used to be.

I think it has something to do with one of my friends. They are just becoming very negative and pissed off about everything. She comes to school every day complaining about how her life sucks and how she can't get her homework done, blah, blah, blah. She reminds me of a friend I lost over the summer. One that screwed me over. I'm starting to ignore and tune this girl out, but she just bothers me. Her problems re all her fault, yet she bitches to us. And suddenly, she uses drugs and alcohol which is a really big turn off as a friend, not to mention when she comes to school the next day and brags about it and tells us "what we're missing". I just can't handle or stand her anymore!

I don't know what to do. I'm just stuck in a rut- I hope. I don't need anybody else on my bad side. I have enough of those people.