Need help with friends.

Well personally this same thing has happened to me. My best frined slipped between my fingers and started to befriend this other girl. Oh how much i dreaded even seeing them together. She was a totally different person. Anyways i did nothing and soon things got bad, really bad. She sided with her and soon hated me. She ostracized me and everyone hated me (the girls in my class actually). All my "friends" vanished. It was horrible. I seriously was depressed. I had no one and i resorted to sweets. I gained like 30 lbs (i didnt get obese or anything bc i was literally a stick before that). Anyways you should confront her even if you cry.tell her that you miss her and how you guys were always doing stuff etc but now it has changed. Tell how you feel. That was my mistake. I did nothing. Do something, you will feel better.

I agree with A98_:) the same thing happened to me but with all my best friends that I've been friends with for 5 years. They all went in different directions and have different friends.I know how you feel. You should talk to her about it but sometimes no matter how hard it is it might be best to let her go and find new friends or go back to your others. You shouldn't leave it alone though. Do something about it. I did nothing and I feel torn up every day about it. Don't make the same mistake as me

I would say not to be worried but when you mentioned her becoming a different person that's a point at which it's normal to be concerned as well as it could be dangerous if she's changing for the worst. I would confront her and talk to her about this. Say you're worried about her changing and that this new friend could be influencing it and give examples to her. If she starts to hate you for it, I would leave her alone, it might not be good for you. I'm sure as well you have other friends that you could be getting closer to if your (old) best friend decided to become a bad person.