I don't know what to do about my best friend

The problem is that when I first moved to my current like town, she was my first friend and now weve been BFFs for almost 3 years. But last year she started becoming friends with this other girl thats a rlly bad influence and now is kind starting ti turn into her. She also sometimes like ditches me for her and on her birthday went out to lunch with that whole "group" (including the bad influence girl) without me even though she knew I wanted to celebrate her birthday with her too. She also like brags a lot in front of me like saying that for her birthday she is gettkng $2,000 earlings and the iphone X, a new apple watch, etc… Even though i've clearly heard her parents say no. I'm just stuck in wether to keep being friends with her cuz although she can be kinda annoying, it would be hard to forget her as a friend, and when I hang out with her I forget about everything she does.

No

I'd remain friends, maybe become more like acquaintances. For now, I'd test your waters with other groups of people to hang out with/other friends. Then, you could hang with them, but still chat with your old BFF. You don't want to be negatively influenced! Be smart and safe in your moves as much as possible.

This happened with my friend too. Started getting really distant and hung with the "wrong" kind of people. Luckily, we were in final year of secondary so I broke it up with her. Not necessarily intentionally, it just happened over time because she went to college and I stayed in my sixth form. I feel that you should gradually try fading her out. Obviously, since you've been really close for a pretty long time, it's almost impossible to just cut it off. So maybe just try and hang out with other people a bit more. If she asks if you want to hang out, from time to time just make some excuse and say that you're busy, or you're hanging out with other people etc.