My friend is playing mind games with me. What should I do?

She always seems jealous of me but for some reason idk why I like her as a friend. My relatives say she's like a crutch to me and I don't need her but to me that's really stupid advice she's my closest friend. So I'm not going to stop being friends with her. A few years ago she stopped being as "supportive" and like started calling me "b****" (in public for 0 reason and I think I have more integrity than her...I know it's her with the problem, not me) like I just want to be happy and in a good mood and then she has to like bring it down by telling me "b****" like why can't we just be happy and be friends and in a good mood like be glad we're friends. And I like to get along with people and be in a good mood and nice. Like the world is just better that way (who wants to be insecure and mean). So on her facebook she had all these posts that were getting on my nerves and one of her posts was stupid and racist so I deleted her off my friends (w/o telling her). And months later she tries adding me again. She never ever asks why or anything like why did I delete her or why this or that. Like she calls me b****, then she tries adding me on facebook, wtf? How should I handle this? I feel like she was my closest friend but she doesn't support me (whenever she sees me happy or about to succeed she calls me b****). So it's like......her as a close friend is there for support but whenever she sees me succeeding she has to bring me down. And this "thing" that's been going on has been going on for 3 years you'd think she'd just f*** me up and keep me out of her life like mutually but she doesn't. I mean if she's so insecure and wants to break off all contact she should do that instead of lying to herself and telling me she's not insecure by adding me, when I have cut her off multiple times.