I need some advice on what to do about my best friend.....?

Honestly a best friend wouldn't do that even if you stopped being friends with them.The best thing I can come up with is to keep ignoring her and if you want to you can write whatever comes to mind on paper or something but, when you're done with what you're writing do what you think is best. Don't let her ruin your life. She may have been a part of it earlier in the years but, she's obviously not a part of it anymore. It's your life for a reason,keep it that way,and don't let her ruin things for you because things get worse.