I think it really depends. Is she always like this? How long has it been going on? I was in a similar situation, but it had been going on for as long as I knew the girl. It took me a long time to realize that my so-called best friend wasn’t really a friend at all in any sense of the word. She and I had been friends since high school and used to hang out every Friday night, but still she was always resentful of my happiness and jealous whenever I had a boyfriend. For example, if my boyfriend held my hand or put his arm around me or anything like that (we wouldn’t dare kiss in front of her), she’d call him an “octopus” and say that we were all over each other, even when I was in a long-distance relationship and she knew that I had very limited time to be with my boyfriend in person. A lot of other things went on like how she used to say mean things about me behind my back to our mutual friends.
When I finally got engaged (not to the same man, in case you were wondering), her negativity became too much for me to tolerate anymore. She didn’t even congratulate me when I told her that I was getting married, she picked fights with me, she kept trying to convince me to wait before I got married, she got mad at me every time I bought something for the wedding saying that I might not need it, I started seeing a lot less of her, I always had to call her first, she’d post on Facebook all day long but then say that she was too busy to hang out with me, she wouldn’t offer me any help with wedding ideas (she would just tell me to research it for myself online) only for her to then criticize every idea that I came up with, and the real kicker… for the “honor” of having her in my wedding party, I would have to pay for her bouquet, dress, jewelry, shoes, purse, manicure, pedicure, make-up, and hairstyling! Oh, and she said I should also do it for each of the girls in the wedding party. Probably so I wouldn’t be able to afford it.
When I wrote her a heartfelt letter (and I fully admit that my first mistake was writing her a letter rather than telling her in person) telling her how much her behavior was hurting me and asking for us to try to fix our friendship, she came back with a very nasty and sarcastic response so I decided that enough was finally enough and I haven’t spoken to her since. Sure, it hurt at the time, but it was one of the best decisions I’ve ever made because now that I don’t have to deal with her negativity anymore, I find myself wondering WHY in the world I ever put up with so much of it in the first place. Why did I ever associate myself who obviously hated to see me happy and was actively trying to interfere with that happiness?
My mother-in-law even told me, “She’s not your friend, she’s your enemy,” and she was absolutely right, but I’m not sure if this is true for you or not. What you have to ask yourself is what you will lose if you stop associating with this girl and what you would gain by keeping her as a friend. If the answer to both questions is “Nothing,” then you know what you need to do.